JP7523793B2 - Migration evaluation device - Google Patents

Description

The present invention relates to a method and device for evaluating a bonding layer (solder part, etc.) that bonds a terminal electrode of a semiconductor component, electronic component, etc. to an electrode of a printed circuit board. By evaluating the bonding layer, it is possible to evaluate the deterioration and lifespan of the bonding layer, as well as to evaluate thermomigration (TM) and electromigration (EM).

The present invention relates to a bonding layer evaluation device and a bonding layer evaluation method used for thermomigration (TM) and electromigration (EM). It also relates to a heater chip for heating a bonding layer, a method for using a heater chip, a manufacturing method for a heater chip, a control method for a heater chip, a bonding layer evaluation method using a heater chip, an evaluation device using a heater chip, etc.

Currently, there is a trend for electronic devices to become smaller and thinner, and to have higher functionality and precision. An important technology supporting this trend is surface mounting technology. This surface mounting technology is a technology for mounting and connecting chip components, mainly ICs and LSIs, and electronic components to high-precision printed circuit boards, and is the trump card of high-density mounting methods.

As electronic circuit boards become more precise and mounted components become smaller and narrower in pitch, the bonding between the electrodes of chip components and electronic components and the electrodes of electronic circuit boards is becoming more important. Therefore, there is a demand for technology that can quantitatively evaluate the bonding condition of the bonding layer between electrodes.

Patent Publication 2012-178449

A conventional method for diagnosing deterioration of the bonding layer between electrodes involves mounting electronic components including semiconductor chips on an electronic circuit board via solder containing nanocarbon on the wiring portion, measuring the temperature distribution of the electronic components while heating the electronic components or electronic circuit board, and detecting deterioration of the bonding layer caused by the solder based on the measured data of the temperature distribution.

However, there were issues with this, such as the need to use solder containing nanocarbon to improve the thermal conductivity of the solder joint layer, and the fact that deterioration could not be diagnosed unless the joint layer was heated until cracks or other defects appeared. In addition, there were issues with the fact that the state of deterioration and deterioration lifespan differed depending on the heating temperature, making it impossible to quantitatively evaluate the state of the joint layer.

In conventional evaluations of the bonding layer 105, it was necessary to use solder containing nanocarbon for the bonding layer 105. Therefore, it was not possible to use the bonding layer 105 material that is actually used. This resulted in discrepancies between the evaluation results and those of the actual product.

In addition, in conventional evaluations of the bonding layer 105, the area including the bonding layer 105 was cut and polished, and then optical observation or SEM observation was performed. This resulted in a destructive evaluation of the bonding layer 105, and it was not possible to evaluate the bonding layer 105 in a non-destructive manner.

In the present invention, both sides of the SiC substrate 106 are roughened using femtosecond laser light or the like, and a thin-film heater 117, temperature probe 116, and current application path 124 are formed with Ni-P film 111 at the roughened areas. Terminal electrodes are placed on both ends of the thin-film heater 117 and on the temperature probe 116, allowing current to be applied to the thin-film heater 117, thereby forming the heater chip 109.

The SiC substrate 106 and the copper plate 104 are connected with sintered Ag paste 125. A constant current 128d is supplied to the terminal electrode 115 from a thermomigration (TM) DC power supply device 803b to the thin film heater 117. A constant current 128a is supplied to the current application path 132 from an electromigration (EM) DC power supply device 803c.

A predetermined constant current is applied to the thin film heater 117 serving as the heater chip 109, and the heat generated by the constant current heats the bonding layer made of solder or the like, while the polished portion of the end surface is observed or measured with an infrared thermography camera or the like. The observation or measurement is performed through the polyimide film 107. The temperature of the bonding layer of the polished portion is measured at multiple points, and temperature information ΔT between the multiple points is obtained.

The heater chip 109 heats a bonding layer made of solder or the like, and the temperature of the bonding layer is measured with an infrared thermography camera or the like to obtain temperature information (temperature distribution) Δ (delta) T between multiple points. The state of the bonding layer can be quantitatively evaluated without contact using the temperature information ΔT.

Based on the temperature information (temperature distribution) ΔT of the temperature distribution, it is possible to easily detect deterioration of the bonding layer or the characteristics of the bonding layer. It is also possible to easily evaluate the lifespan of the solder bonding layer. Furthermore, the detection of the deterioration state and the evaluation of the lifespan are highly reliable.

FIG. 2 is an explanatory diagram of a bonding layer evaluation device according to the present invention. 1A and 1B are a configuration diagram and a cross-sectional view of a heater chip according to the present invention. 4A to 4C are explanatory diagrams of a manufacturing method of the heater chip of the present invention. 4 is a flowchart of a method for manufacturing a heater chip of the present invention. 1A to 1C are explanatory diagrams of a manufacturing method of a heater chip according to the present invention. 1 is an explanatory diagram of a configuration of a bonding layer evaluation device and an evaluation method according to the present invention. 1A and 1B are a configuration diagram and a cross-sectional view of a heater chip according to the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer according to the present invention. 4 is an explanatory diagram of the operation of the bonding layer evaluation device of the present invention. FIG. 4 is an explanatory diagram of the operation of the bonding layer evaluation device of the present invention. FIG. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer according to the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer according to the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer according to the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer according to the present invention. FIG. 13 is an explanatory diagram of a thermal simulation of the bonding layer of the present invention. 2A and 2B are a plan view and a cross-sectional view of a heater chip in an embodiment of the present invention. FIG. 2 is a plan view of a heater chip according to an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer in an example of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. 2A and 2B are a plan view and a cross-sectional view of a heater chip in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a heater chip according to an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. 5A to 5C are explanatory diagrams of a manufacturing method of a heater chip in an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating the relationship between a temperature gradient and the occurrence of TM. 1A to 1C are explanatory diagrams of a method for evaluating a heater chip and a bonding layer in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer in an example of the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer in an example of the present invention. FIG. 2 is an explanatory diagram of a bonding layer in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a method for evaluating a bonding layer in an example of the present invention.

The bonding layer evaluation method and bonding layer evaluation device according to the embodiment of the present invention, and the heater chip of the present invention will be described below with reference to the attached drawings.

In the embodiment described in the specification, a bonding layer formed between electrodes by solder is evaluated. However, the present invention is not limited to bonding layers made of solder or the like.

For example, it goes without saying that the present invention can be applied to a bonding layer bonded with silver paste or copper paste, a bonding layer formed by electrical discharge machining, a bonding layer formed by high-frequency induction heating, a bonding layer formed by electromagnetic induction heating, a bonding layer bonded by pressure bonding, etc. The bonding layer 105 is not limited to conductive materials, and may be, for example, an organic insulating material such as acrylic resin or epoxy resin.

The present invention observes a bonding layer that is placed or formed between heated or overheated electrodes, etc., using a temperature detection means such as an infrared thermography camera. Therefore, it is not limited to electronic components or wiring boards that have electrodes. It may also be a system that applies a lock-in signal current to an object and measures infrared rays from the object in synchronization with the lock-in signal.

The connection portion 105 is sometimes called a bonding layer 105. The bonding layer 105 is not limited to being layered, and may be formed or configured three-dimensionally or independently as the bonding layer 105. It may also be configured with different members arranged in close contact. The present invention can be applied to a wide variety of configurations or structures of the connection portion.

In each drawing for explaining the form for carrying out the invention, elements having the same function are given the same reference numerals, and explanations may be omitted. Furthermore, the embodiments of the present invention may be combined with each other. Furthermore, in order to facilitate illustration and understanding, the configuration of the present invention may be illustrated as being thick or thin, and the components may be shown reduced or enlarged.

Figure 2 shows a plan view and a cross-sectional view of the heater chip 109 of the present invention used in the bonding layer evaluation device of the present invention. Figure 2(a) is a plan view of the heater chip 109. Figure 2(b) is a cross-sectional view taken along line AA' in Figure 2(a), and Figure 2(c) is a cross-sectional view taken along line BB' in Figure 2(a).

An example of the base substrate 106 is silicon carbide (SiC). SiC is a compound semiconductor material composed of silicon (Si) and carbon (C). Single crystals of SiC have high thermal conductivity, small internal temperature distribution, and a high heat resistance, making them preferable for the base substrate 106. Other examples of the base substrate 106 include glass substrates such as sapphire glass, which are insulating and have good thermal conductivity, and ceramic substrates made of alumina or silicon nitride.

Materials such as SiC ceramics, AlN ceramics, AlN (aluminum nitride), or substrates filled with AlN do not conduct electricity but are good conductors of heat, and can therefore be used as the substrate 106 of the heater chip 109 of the present invention.

An example of the base substrate 106 is aluminum nitride (AlN). AlN is a nitride of aluminum and is a colorless and transparent ceramic. It is also called aluminum nitride. AlN has a high thermal conductivity of 180 and 230 W/mK.
As the base substrate 106, BeO (beryllium oxide, commonly known as beryllia) can be used since it has a high thermal conductivity of 270 W/mK.

AlN can be processed into ceramic products by processing it into disks using a hot press or other method, but it is basically in powder form. It is necessary to control the particle size of the powder, and the reduction nitridation method makes it possible to produce powder with a particle size ranging from 0.1 μm or less to around 10 μm. When used as a filler in silicon resin, etc., the filling rate of the filler can be improved by combining AlN particles with different particle sizes.

In the reduction nitridation method, a mixture of alumina (Al ₂ O ₃ ) and carbon (C) is nitrided to produce AlN. The mixture is then oxidized to cover the surfaces of the AlN particles with an oxide film. Compared to the direct nitridation method, the thickness of the surface oxide film is about 11 Å (angstroms), twice as thick. The final oxidation process removes the imide groups (N-H) and amide groups (N-H ₂ ) from the particle surfaces, producing pure AlN particles.

For ease of explanation, the present specification will describe the base substrate 106 as being made of SiC. Needless to say, any substrate that has good thermal conductivity and is insulating or semiconducting can be used as the base substrate 106.

The thickness of the base substrate 106 is 0.1 mm or more and 0.8 mm or less. The thinner the base substrate 106, the easier it is for heat from the thin-film heater 117 to be transferred to the bonding layer 105. However, if the base substrate 106 is thin, a temperature distribution is likely to occur in the bonding layer 105 between areas where the thin-film heater 117 is formed and areas where it is not formed. The size of the heater chip 109 is 3 mm square or more and 10 mm square or less.

In the present invention, a thermal simulation is performed taking into consideration the wiring width of the thin film heater 117 of the heater chip 109, the formation area of the bonding layer 105, and the thickness of the bonding layer 105. The size and thickness of the heater chip 109 are designed through the thermal simulation. In Fig. 2, as an example, the size of the heater chip 109 is a width W1 of 3 mm or more and 30 mm or less, and a width W2 of 3 mm or more and 30 mm or less.
The thin film heater 117 and the temperature probe 116 are made of or consist of Ni (nickel)-P or Ni.

A thin film (Ni-P film 111d) is formed on the back surface of the SiC substrate 106 by nickel-phosphorus (Ni-P) plating, and a gold plating film 112c is formed on the surface of the Ni-P film 111d. Although the thin film 111 is described as a Ni-P film, the thin film 111 may also be formed of Ni or Ni-B. The thin film 111 may be made of any material as long as it can be bonded closely to the bonding layer 105.

Other than nickel (Ni), examples include tin, silver, gold, copper, lead, zinc, and alloys of these. However, an appropriate resistance value must be present, since the thin film heater 117 and the like are used as heating elements.

In the present invention, a nickel (Ni) film or a nickel-phosphorus (Ni-P) film is exemplified, which can be in close contact with the bonding layer 105 and has a relatively high resistance value for use as the thin film heater 117. Hereinafter, in the present specification and drawings, the thin film 111 will be described as a Ni-P film 111 for ease of explanation.
The thickness of the Ni--P film 111d is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 6 μm or less.

The thickness of the gold (Au) plating film 112c is 0.01 μm or more. The gold plating film 112c has the function of preventing or suppressing oxidation or contamination of the surface of the Ni-P film 111d.

A thin film heater 117 and a temperature probe 116 are formed on the surface of the SiC substrate 106. The thin film heater 117 and the temperature probe 116 are formed of a thin film (Ni-P film 111d) by Ni-P plating. They may be made of or formed of platinum (Pt) other than Ni. Other materials that can be used include zinc, tin, lead, and chromium. They can also be made of materials other than metals, such as carbon (C).
As shown in FIG. 3, the film thickness (μm) of the thin film heater 117 and the sheet resistance value (Ω/sq) of the thin film heater 117 have an approximately linear relationship.

However, as shown in FIG. 3, as the film thickness of the thin-film heater 117 increases, the sheet resistance value (Ω/sq) tends to become relatively smaller and the relationship becomes nonlinear (film thickness (μm) of the thin-film heater 117>10.0 (μm)). Also, as the film thickness of the thin-film heater 117 decreases, the sheet resistance value (Ω/sq) tends to become relatively higher and the relationship becomes nonlinear (film thickness (μm) of the thin-film heater 117<0.1 (μm)). This is thought to be due to the roughened surface state of the SiC substrate 106 and the curved shape of the thin-film heater 117.

It is preferable to adopt a region in which the film thickness of the thin-film heater 117 and the sheet resistance value (Ω/sq) have a linear relationship. Therefore, the film thickness of the thin-film heater 117 is preferably 0.1 (μm) or more and 7.5 (μm) or less, and the sheet resistance value (Ω/sq) is preferably 0.25 (Ω/sq) or more and 1.00 (Ω/sq). The resistance value of the thin-film heater 117 is preferably 5 Ω or more and 300 Ω or less.

The temperature probe 116 is formed from the same material and in the same process as the thin-film heater 117. If the thin-film heater 117 is a Ni-P film, the temperature probe 116 is also formed from a Ni-P film. The temperature probe 116 is formed with a narrow wiring width to increase the resistance over its entire length.

A constant current is applied to the temperature probe 116. Increasing the resistance of the temperature probe 116 increases the change in resistance, and increases the change in voltage between the terminals of the temperature probe 116 in response to the constant current. This improves the sensitivity of the temperature probe 116 to temperature changes in the thin film heater 117. The resistance of the temperature probe 116 is set to 20 Ω or more and 1 kΩ or less.

Terminal electrodes 114a and 114b are formed on both ends of the temperature probe 116. Terminal electrodes 115a and 115b are formed on both ends of the thin film heater 117. A gold plating film 112 is formed on the surface of the terminal electrode 114, etc. A gold plating film 112 is formed on the surface of the terminal electrode 115, etc. The thickness of the gold plating film 112c is 0.01 μm or more.

The gold plating film 112 is not formed on the thin film heater 117 and the temperature probe 116. If the gold plating film 112 is formed, the resistance value of the thin film heater 117 and the temperature probe 116 will decrease, and the sensitivity to heat generation or temperature changes will decrease.

A SiO ₂ film, a SiN _x film, or a SiON film may be formed on the thin film heater 117 and the temperature probe 116 to prevent the surfaces of the thin film heater 117 and the temperature probe 116 from being oxidized or contaminated.

117 will be described as a thin-film heater, but is not limited to this. Thin-film heater 117 is arranged or formed to heat substrate 106. As an alternative to thin-film heater 117, a surface heater incorporating Nichrome wire, a heater using a Peltier element, etc. may be used. The base substrate 106 can be heated by passing a current through a surface heater incorporating Nichrome wire or a Peltier element.

Lead wires 121 are soldered to terminal electrodes 114 and 115, or a probe (not shown) is pressure-welded to terminal electrodes 114 and 115, and a constant current output by current power supply device 803 is applied to terminal electrodes 114 and 115.

Figures 4 and 5 are explanatory diagrams of the manufacturing method of the heater chip 109 of the present invention. Figure 4 is a flowchart showing the manufacturing method of the heater chip. Figures 5(a) to 5(f) are explanatory diagrams for explaining the manufacturing method of the heater chip 109.

A mask 501 is applied to the surface of the SiC substrate 106 (FIG. 4 S11, FIG. 5(b)). The mask 501 is preferably one that contains an alkali-soluble acrylic polymer.

Next, the surface of the SiC substrate 106 is roughened using a femtosecond laser device (FIG. 4 S12, FIG. 5(c)). Femtosecond laser light 502 or picosecond laser light 502 is irradiated to remove the portions of the surface of the SiC substrate 106 that correspond to the thin-film heater 117, temperature probe 116, terminal electrode 114, and terminal electrode 115, forming a rectangular groove-shaped recess 503. The bottom and side surfaces of the recess 503 are roughened (roughened) by irradiation with the femtosecond laser light 502, etc.

The roughening using the femtosecond laser light 502 is also performed on the areas corresponding to the terminal electrodes 114 and 115. A Ni-P film 111 is formed on the roughened areas.

The terminal electrodes 114 and 115 have large roughened areas, while the temperature probe 116 has a narrow roughened line width. It is preferable to change the roughened state of the temperature probe 116 depending on the roughened area so as to increase the roughening (to deepen the unevenness caused by the roughening).
The roughened state can be easily achieved by changing or setting the laser intensity of the femtosecond laser light 502 and the moving speed of the irradiated laser pulse.

The Ni-P film 111d is also formed on the back surface of the SiC substrate 106. Therefore, the portion of the SiC substrate 106 where the Ni-P film 111d is to be formed is also roughened by the femtosecond laser light 502.

A femtosecond laser device generally generates femtosecond laser light 502 with a pulse width of subpicoseconds to tens of femtoseconds. When an ultrashort pulse of laser light 502 of subpicoseconds to tens of femtoseconds is irradiated onto a material, the pulse width is sufficiently short compared to the thermal diffusion characteristic time of the material, so that light energy can be effectively input to the irradiated area.

As a result, it is possible to limit the thermal effects to the periphery of the irradiation, enabling highly accurate micromachining. In addition, because the electric field strength of the laser light is extremely high, it is possible to induce nonlinear effects such as multiphoton absorption and multiphoton ionization in a spatially selective manner only where the beam is focused.

By irradiating a pulse of femtosecond laser light 502, the portions of the mask 501 corresponding to the portions where the thin film heater 117 and temperature probe 116 are to be formed are removed, forming recesses 503.

Patterning of wiring (thin film heater 117, temperature probe 116, etc.) may be performed based on marks formed on the surface of mask 501. Positioning is performed based on cross marks 130 (not shown) formed on SiC substrate 106, etc.

The cross mark 130 formed on the SiC substrate 106 is captured by a camera, the cross mark 130 is image-recognized, the position of the cross mark 130 is compared with the design coordinates, and the patterning (thin film heater 117, temperature probe 116, etc.) position (the location where the laser light is irradiated) is positioned, and the laser light 502 is irradiated.

The SiC substrate 106 is degreased using an acidic degreaser at 45°C for 5 minutes (Fig. 4, S13). A pre-dip process is performed using a hydrochloric acid aqueous solution (Fig. 4, S14). The retention time is, for example, 2 minutes.

Next, the Sn-Pd catalyst 504 is applied to the surface of the recess 503 and to the surface of the remaining part of the mask 501 (Fig. 4 S15, Fig. 5 (d)). The Sn-Pd catalyst 504 is a colloidal particle, and a Sn-rich layer and a Sn2+ layer are formed in that order on the surface of the Sn-Pd core.

Next, activation is performed (Fig. 4 S16). The SiC substrate 106 with the Sn-Pd catalyst 504 applied is immersed in a hydrochloric acid solution to remove the Sn layer and expose the internal Pd catalyst. Since the Pd catalyst is exposed, a reaction occurs with the electroless Ni-P plating solution in the area where the Sn-Pd catalyst 504 is present.

The mask 501 is peeled off using an alkaline solution (S17 in FIG. 4, FIG. 5(e)). The Sn-Pd catalyst 504 is not present in the portion of the SiC substrate 106 where the mask 501 has been peeled off.

The mask 501 is peeled off using an alkaline solution (S17 in FIG. 4, FIG. 5(e)). The Sn-Pd catalyst 504 is not present in the portion of the SiC substrate 106 where the mask 501 has been peeled off.

Electroless Ni-P plating is performed on the surface of the SiC substrate 106 to form the thin film heater 117 and temperature probe 116 (Fig. 4 S18, Fig. 5 (f)). As the electroless Ni-P plating solution, a reduction precipitation type electroless Ni-P plating solution that uses sodium hypophosphite as a reducing agent in the acidic to neutral range can be used.

As the chelating agent, malic acid, citric acid, malonic acid, tartaric acid, and other oxycarboxylic acids, acetic acid, succinic acid, and other monocarboxylic acids, and ammonia, glycine, and other amines can be used alone or in combination.

Pd is added to act as a catalyst so that the reducing agent in the electroless Ni-P plating solution releases electrons on the SiC substrate 106. Therefore, the Ni ions in the electroless Ni plating solution are reduced by the electrons released by the oxidation reaction of the reducing agent, and are precipitated on the surface of the SiC substrate 106, forming the thin-film heater 117 and the temperature probe 116.

According to this embodiment, Ni-P plating with good adhesion can be easily performed on the SiC substrate 106, which is made of a material that is difficult to plate, without using special chemicals or photolithography techniques.

In this embodiment, a mask 501 is used, and plating is performed by leaving the Sn-Pd catalyst 504 only on the roughened parts of the SiC substrate 106 corresponding to the thin-film heater 117 and temperature probe 116. This ensures good patterning accuracy for the thin-film heater 117 and temperature probe 116, and does not require surface polishing.

The wiring pattern can be easily formed while the areas other than those corresponding to the wiring pattern are protected by the mask 501. Electroless Ni-P plating is performed only on the roughened area 111, so that a thin-film heater 117 etc. can be formed to the desired thickness.

Multiple heater chips 109 are fabricated simultaneously in a matrix on one SiC substrate. After the Ni-P film is formed, the outer frame of each heater chip 109 is irradiated with a carbon dioxide laser beam, a YAG laser beam, or the like, and cut (laser dicing) and separated into individual pieces. Alternatively, the heater chips 109 may be separated into individual pieces by dicing (wet) or scribing (dry).

Figure 6 is an explanatory diagram of the configuration of a bonding layer evaluation device according to an embodiment of the present invention. Figure 6(a) shows a fabricated heater chip 109. The heater chip 109 in Figure 6(a) is bonded to a copper plate 104 by a bonding layer 105, as shown in Figure 6(b).

For ease of explanation, the copper plate 104 will be described as a substrate made of copper, but this is not limited to this. Any substrate or sheet with good thermal conductivity may be used. For example, a substrate or sheet made of carbon graphite is an example.

The copper plate 104 is a copper plate having a thickness of 0.1 mm or more and 2 mm or less. The copper plate 104 is preferably an oxygen-free copper plate. A Ni-P film 111a is formed on the surface of the copper plate 104. Furthermore, a Ni-P film 111b is formed on the surface of the copper plate 104. The film thickness and formation method of the Ni-P films 111a and 111b are similar to those of the Ni-P film 111a, so a description thereof will be omitted. Furthermore, it is preferable to form gold on the surface of the Ni-P film 111 by gold plating.

In the embodiment of the present invention, 104 is described as a copper plate, but this is not limited to this. As long as the Ni-P film 111 that bonds with the solder is well formed on the surface of the plate 104 and the plate has good thermal conductivity, the plate 104 may be made of a material other than copper. For example, it may be silver (Ag), titanium (Ti), ceramic, etc.

Examples include a ceramic plate, a stainless steel plate, a nickel plate, and a silver plate. For ease of explanation, this specification will be described as a copper (Cu) plate 104.

A gold plating film 112a is formed on the surface of the Ni-P film 111a, and a gold plating film 112b is formed on the surface of the Ni-P film 111b. The method for forming the gold plating films 112a and 112b is the same as that for the gold plating film 112c, so a description thereof will be omitted.

The bonding layer 105 to be evaluated is formed between the Ni-P film 112c of the heater chip 109 and the Ni-P film 112a of the copper plate 104. As an example, the bonding layer 105 is solder, and a solder sheet (solder cream) is screen printed on the copper plate 104. The heater chip 109 is mounted on the solder sheet. After mounting, the copper plate 104 and the heater chip 109 are placed together in a reflow furnace set to certain conditions. Note that solder paste may be used instead of the solder sheet.

The bonding layer 105 is not limited to a bonding layer made of solder or the like. For example, it goes without saying that it can be applied to a bonding layer bonded with silver paste or copper paste, a bonding layer formed by electric discharge machining, a bonding layer formed by high-frequency induction heating, a bonding layer formed by electromagnetic induction heating, etc. Also, a bonding layer bonded by pressing an organic material, or an insulator is also a bonding layer, and the temperature information ΔT can be measured by an infrared thermography camera 108, etc.

The infrared thermography camera 108 can measure two-dimensional temperature distribution of the bonding layer 105, etc. By measuring two-dimensionally, it is possible to visually express and measure temperature changes centered around points A, B, etc. However, if the purpose is to obtain temperature information ΔT at a specific position such as point A or point B, the temperature information ΔT can be obtained by measuring with a radiation thermometer.
For ease of explanation, the present specification will be described assuming that the bonding layer 105 is formed by heating a solder cream or a solder sheet in a reflow process.
When soldering using the reflow process, solder cream or the like is printed in advance on the designated locations, and then the solder is heated and melted in a reflow furnace to join the components.

When the solder cream is printed, it looks like the soldering has been done properly, but the solder is still in a fine grain state and cannot function properly. By heating it in a reflow furnace, the solder grains join together, and the flux is vaporized by the heat, so the part becomes the same state as regular solder and is soldered.

The temperature of the molten solder in flow soldering is different from the temperature of the furnace in reflow soldering. It is important to understand the heat resistance of the components used and to design the process appropriately. By measuring the temperature information ΔT of the bonding layer with the bonding layer evaluation device of the present invention, it is possible to quantitatively evaluate the bonding layer and also to carry out detailed design.

In the bonding layer evaluation method and bonding layer evaluation device of the present invention, the heater chip 109 heats the bonding layer 105, and changes or heats it in a different state in response to the heating conditions (reflow furnace conditions). In addition, the bonding layer 105 is formed by varying the material mixture state (mixture ratio of flux and solder, etc.) and the difference in the materials used (difference in flux or solder material, etc.).

The formed bonding layer 105 is measured with an infrared thermography camera 108 to obtain the temperature distribution state, temperature information ΔT, etc. By obtaining the temperature information ΔT, the lifespan and bonding characteristics of the bonding layer are quantitatively evaluated.

As shown in FIG. 6(b), the heater chip 109 and the copper plate 104 are bonded by the bonding layer 105. Next, as shown in FIG. 6(c), the heater chip 109, the copper plate 104, and the bonding layer 105 are simultaneously polished from the A direction to the CC' line.

One example of grinding is the process of quickly rotating a large circular tool called a grinding wheel and bringing the surface of the object to be processed into a smooth surface. The surface of this grinding wheel is fitted with countless large abrasive grains, which can be used to remove tiny protrusions from the surface of the object.

The polishing process is preferably performed by CP (Cross section polisher) processing (ion milling). CP processing (ion milling) is a method of cutting a sample by irradiating a broad, unfocused argon ion beam onto the sample, utilizing the sputtering phenomenon that ejects sample atoms. The argon ion beam is incident on the surface of the sample, and the sample is processed to produce the sample. With CP processing, no heat is generated on the polished surface, and there is no effect of heat on the bonding layer 105.

Next, as shown in FIG. 6(d), a photosensitive polyimide film is formed on the polished surface. The photosensitive polyimide film is formed on the polished surface by a method such as spin coating, slit coating, screen printing, inkjet spraying, spray coating, die coating, doctor knife coating, or flexographic printing. The area where the photosensitive polyimide film is formed includes at least the bonding layer 105.

As shown by the arrow in FIG. 6(d), the exposure is performed by irradiating ultraviolet light, etc., through a photomask having an arbitrary pattern with an exposure dose of 200 to 2000 mJ.

As the developer, an alkaline developer, for example, an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, or aqueous ammonia, can be used. Development is carried out at about 15°C to 60°C for about 0.5 to 10 minutes. Heating for curing is carried out at about 120°C to 200°C for about 30 to 120 minutes.

Objects radiate infrared rays from their surfaces, and the temperature of the object's surface is determined by the amount of infrared rays. Infrared rays also have the characteristic of transmitting energy through space. The infrared thermography camera 108 optically reads the infrared rays that have transmitted through space, and measures the temperature of the object without coming into contact with it. The infrared thermography camera 108 has an autofocus function.

The ratio of the actual amount of thermal radiation energy radiated by the object being measured to the amount of thermal radiation energy of a perfect radiator (black body) at the same temperature is called emissivity.
A perfect radiator (black body) absorbs all the energy incident on it and radiates thermal energy corresponding to its temperature. The infrared thermography camera 108 is calibrated assuming that the emissivity of a perfect radiator (black body) is 1.0, and in actual object measurements, the emissivity is preset and corrected.

If the constituent material or composition of the polished surface differs, the emissivity, which is the ratio of the amount of thermal radiation energy, will differ. However, if corrections are made to the constituent material or composition of the polished surface, there is a possibility that differences will occur due to the corrections. In addition, objects with high reflectivity, such as polished metals, are not suitable for measuring emissivity.

As shown in FIG. 6(d), the present invention forms a photosensitive polyimide film 107 on the bonding layer 105 of the polished surface. If the emissivity of the photosensitive polyimide film 107 is measured and set in advance, the formed bonding layer 105 can be measured with an infrared thermography camera 108, a radiation thermometer, etc., without being affected by the constituent material or composition of the polished surface, and the temperature distribution state, temperature information ΔT, etc. can be obtained with high accuracy. By obtaining temperature information ΔT, etc., the life and bonding characteristics of the bonding layer can be quantitatively evaluated.

In the above embodiment, a photosensitive polyimide film 107 is formed on the polished surface, but this is not limited to the above. For example, a heat-resistant polyimide film 107 may be attached. Also, the heat-resistant polyimide film 107 may be placed in close contact with the bonding layer 105, etc.

Examples of polyimide film 107 or polyamide film 107 include Kapton (registered trademark) from DuPont, Inc., Upilex (registered trademark) from Ube Industries, and Uniamide (registered trademark) from Unitika.

Non-contact temperature measurement means such as infrared thermography cameras 108 and radiation thermometers use infrared radiation to measure temperature, and therefore have a faster response speed than resistance thermometers and thermocouples. They are capable of measuring the temperature of objects with low heat capacity, low thermal conductivity, and objects with a small surface area. Temperature measurement can be performed without contact.

As explained in Figure 6 (c), the observation surface is polished at the CC' line. Polishing smoothes the surface, allowing for good observation. The polished bonding layer may have a high reflectance, in which case it is not suitable for measuring emissivity.

In the present invention, by forming or placing a photosensitive polyimide film, polyimide film 107, polyamide film 107, or the like on the polished surface to be observed, the emissivity from the observation surface can be stabilized and the emissivity can be measured quantitatively.
Incidentally, the emissivity of the photosensitive polyimide film can be stably measured even in the applied state without being cured.

Next, as shown in FIG. 6(e), the copper plate 104 and the heating/cooling plate 101 are attached. As an example, heat dissipation (heat transfer) grease 118 is used for attachment. An example of the heat dissipation (heat transfer) grease 118 is modified silicone grease. It is preferable to use this heat dissipation (heat transfer) grease mixed with metal or metal oxide particles (filler) with high thermal conductivity.

The main particles used are copper, silver, aluminum, etc., but also alumina, magnesium oxide, aluminum nitride, etc. These elements or mixtures are dispersed using a dispersion method appropriate for their particle diameter.

Even if the grease maintains a suitable level of viscosity immediately after application, it may deteriorate and harden over time after use. As a result, cracks may appear in the solidified heat dissipation (heat transfer) grease due to differences in the linear expansion coefficient of the materials being joined, which may result in a decrease in the conductive properties.

The heat dissipation (heat transfer) grease 118 can be connected by simply pressing down on the top and bottom, but if high temperatures are expected, it is preferable to perform low-temperature reflow to ensure a secure bond.

As shown in FIG. 6(e), the bonding layer 105 and its vicinity are observed with an infrared thermography camera 108 or the like through a polyimide or polyamide film or membrane.

The infrared thermography camera 108 is mounted on an XYZ stage 110. The XYZ (X-axis, Y-axis, Z-axis) stage 110 moves and positions in the X-axis direction (left and right direction), the Y-axis direction (the distance between the bonding layer 105 and the camera 108), and the Z-axis direction (up and down direction). The axial movement of the XYZ stage 110 has a positioning accuracy of 1 μm. It also rotates in the θ direction as necessary.

It goes without saying that the heating/cooling plate 101 may be mounted or placed on an XYZ stage 110, and the heating/cooling plate 101 may be moved or positioned in the X-axis, Y-axis, and Z-axis directions.
1 is an explanatory diagram of a bonding layer evaluation method and a bonding layer evaluation device according to the present invention. A circulating water pipe 102 is disposed within a heating/cooling plate 101.

It has a chiller (cooling/warming device) 103, a heating/cooling plate 101, and a circulating water pipe 102 that circulates between the heating/cooling plate 101 and the chiller 103. A heater chip 109 having a bonding layer 105 of the evaluation object and a copper plate 104 are loaded on the heating/cooling plate 101.

A constant current Ib (see FIG. 9) is applied from a current power supply device 803b via terminal electrodes 115a and 115b to the thin film heater 117. A constant current Ia (see FIG. 9) is applied from a current power supply device 803a to the temperature probe 116 via terminal electrodes 114a and 114b.
A constant current Ia is applied to the thin film heater 117 to heat the bonding layer 105. Depending on the evaluation result or during the evaluation, the evaluation of the evaluation sample is stopped or the control method is changed.

A change in the characteristics of the evaluation sample is determined or judged based on the temperature information ΔT or a change in the temperature information ΔT obtained by observation with the infrared thermography camera 108. Alternatively, the characteristics and state of the bonding layer 105 are evaluated.
In the method for evaluating the bonding layer of the present invention, the external conditions are changed or set in accordance with the deterioration or characteristic change of the bonding layer 105 .

For example, if the change in the bonding layer 105 is large or if the temperature of the bonding layer 105 is higher than a predetermined value, the current Ib flowing through the heater chip 109 is reduced. Also, the temperature of the coolant (water, etc.) flowing through the circulating water pipe 102 is lowered. If the change in the bonding layer 105 is small or if the temperature of the bonding layer 105 is lower than a predetermined value, the current Ib flowing through the heater chip 109 is increased. Also, the temperature of the coolant (water, etc.) flowing through the circulating water pipe 102 is raised.

The chiller 103 is configured to keep the temperature of equipment, etc. constant by circulating water or heat transfer medium while managing its temperature. It is primarily used for cooling, but can also heat as well as cool. It is configured to be able to control a variety of temperatures.

Note that although circulating water is described in this specification, it is not limited to water. It may be ethylene glycol, glycerin, etc., or forced air cooling. The chiller 103 controls the liquid in the circulating water pipe 102 to a temperature range of, for example, -1°C to +100°C, and supplies it to the heating and cooling plate 101 of the test unit. The heating and cooling plate 101 has a sufficiently large heat capacity.

In the above embodiment, a heating/cooling plate 101 is used, but the heating plate and cooling plate may be separate, and heating and cooling may be performed using a heat source or cold source other than the heating/cooling plate.

The bonding layer evaluation method and bonding layer evaluation device of the present invention quantitatively evaluate the bonding layer 105 by measuring or acquiring the temperature distribution state of the bonding layer 105 and its vicinity.

The characteristics of the bonding layer 105, etc. vary depending on the state of voids in the bonding layer 105, the alloy ratio of the metal material of the solder, the flux content, the type of metal material of the solder, and the melting ratio of impurities in the metal material of the solder. These also change or differ depending on the reflow conditions (temperature, time, rate of temperature change), etc.

Normal voids are mainly caused by gasified flux remaining in the fillet. If the lead is thin or small, and there is a sufficient amount of solder, this can be largely eliminated by extending the time above the melting point. This is because the flux effect suppresses the surface tension of the molten solder, and gas is released from inside the fillet through thermal convection, eliminating the problem. At the same time, gas is also released from the board and the surfaces of the component leads.
In the case of packaged or mounted component forms such as BGA and CSP, solder is printed underneath the component, so the generated gas tends to remain underneath the component. However, there is a gap between the component and the board the size of the ball, so as long as the fluidity of the solder is maintained, the gas will be released from within the ball to the outside.
Conversely, in leadless and power components, there are no gaps between the component and the board land, so generated gases and flux residue remain underneath the component, forming large voids.
Voids occur when gas generated during mounting cannot be discharged to the outside due to insufficient solder fluidity or short melting time.

Electronic components, circuit boards, and solder paste absorb moisture, which is released as water vapor during reflow. Gaps between particles that occur during solder printing become voids after reflow. If a printed wiring board or electronic component has a recess, and is mounted on it, a gap will form between the recess and the component, preventing the solder from flowing in and creating a void. If there is a void in the path of a crack, the crack will progress faster. A relationship has been shown between the void occupancy rate and fatigue life.

The bonding layer evaluation method and bonding layer evaluation device of the present invention are effective in quantitatively evaluating the state of the bonding layer 105 and the vicinity of the bonding layer 105 by acquiring the temperature distribution state, temperature information ΔT, etc.

The temperature information ΔT is large in areas where deterioration has occurred in the bonding layer 105 due to thermal fatigue testing and in the surrounding area. The temperature information ΔT changes depending on the overheating (heating) state and overheating (heating) time caused by the heater chip 109. By measuring the temperature distribution after the passage of time, it is possible to predict the lifespan of the bonding layer 105.

By using the bonding layer evaluation method and bonding layer evaluation device of the present invention, the occurrence of cracks can be confirmed at an early stage of heating. In addition, by using the bonding layer evaluation method and bonding layer evaluation device of the present invention, it is possible to acquire or measure temperature information ΔT and temperature distribution data based on the void distribution state, flux distribution state, metal or composition material of the bonding layer 105, alloy state, etc.

The state of the bonding layer 105 can be quantitatively evaluated based on the acquired or measured temperature information ΔT and temperature distribution data. In addition, the characteristics, life prediction, and failure rate of the bonding layer 105 can be quantitatively evaluated and determined.

By using the bonding layer evaluation method and bonding layer evaluation device of the present invention, it is possible to easily grasp, calculate, or obtain the remaining lifespan of the bonding layer 105 in a non-destructive manner by calculating the rate of progression of the deterioration and determining whether the deterioration is progressing.
In order to perform a deterioration diagnosis of the bonding layer (bonding layer) 105, first, a temperature difference is extracted from the measurement data of the temperature distribution, and if necessary, a temperature difference over time is also extracted.

The extracted data can then be analyzed to evaluate the characteristics of the bonding layer 105 and detect any deterioration or changes in the bonding layer 105. Analysis of this data can also be used to evaluate or predict the lifespan of the bonding layer.

In the case of an infrared thermography camera, the measurement data of the temperature distribution can be displayed as an image, and the temperature difference over time can be extracted from the obtained data image, making it possible to identify the locations where cracks, peeling, etc. have occurred. By measuring the length and size of the cracks, it is possible to analyze the measurement data of the temperature distribution. It is also possible to evaluate the characteristics of the bonding layer 105, and detect deterioration or changes in the bonding layer 105.

Figure 9 is an explanatory diagram of the bonding layer evaluation method and bonding layer evaluation device of the present invention. Temperature information ΔT from a radiation thermometer or an infrared thermography camera 108 is input to the control circuit 804, and the chiller 103 is controlled based on the temperature information ΔT. Alternatively, the chiller 103 is controlled so that the temperature information ΔT becomes a predetermined value.

The control circuit 804 controls the XYZ stage 110 to move the infrared thermography camera 108 and position it at a predetermined position on the bonding layer 105. It also changes the position of the bonding layer 105 at predetermined intervals to obtain temperature information ΔT.

The control circuit 804 controls the constant current circuit 802a and the switch circuit 801a of the current power supply device 803a to apply a constant current Ia to the temperature probe 116. The constant current Ia is applied between the terminal electrodes 114a and 114b.

The control circuit 804 controls the constant current circuit 802b and the switch circuit 801b of the current power supply device 803b to apply a constant current Ib to the thin film heater 117. The constant current Ia is applied between the terminal electrodes 115a and 115b.

The thin film heater 117 generates heat due to the constant current Ib, and the generated heat is transferred to the SiC substrate 106 and heats the bonding layer 105. The heat temperature of the thin film heater 117 increases the resistance value of the temperature probe 116.

A thin-film heater 117 is formed or disposed around the temperature probe 116. The heater chip 109 is configured so that the temperature of the thin-film heater 117 and the resistance value of the temperature probe 116 have a linear relationship.

A constant current Ia is supplied to the temperature probe 116. When the resistance value of the temperature probe 116 increases, the voltage between the terminal electrodes 114a and 114b of the temperature probe 116 also changes in proportion to the temperature. By measuring the voltage between the terminal electrodes 114a and 114b of the temperature probe 116 with the voltmeter 122a, the heat generation temperature of the thin film heater 117 (the temperature of the SiC substrate 106) can be obtained.

In this specification, the refrigerant flowing through the circulating water pipe 102 is described as circulating water, but it is not limited to water. It may be ethylene glycol, glycerin, freon, etc., or it may be forced air cooling.

The chiller 103 controls the liquid in the circulating water pipe 102 to a temperature range of, for example, -1°C to +100°C, and supplies it to the heating and cooling plate 101 of the test unit. The heating and cooling plate 101 has a sufficiently large thermal capacity.

In the embodiment of the present invention, a heating/cooling plate 101 is used, but the heating plate and cooling plate may be separate, and heating/cooling may be performed using a heat source/cold source other than the heating/cooling plate.

The current power supply device 803 outputs a constant current Ia or a constant current Ib to be supplied to the thin-film heater 117 or the temperature probe 116. The current power supply device 803 supplies power (current, voltage) to the thin-film heater 117 or the temperature probe 116 in synchronization with a control signal from the control circuit 804. The current power supply device 803 can also set the maximum voltage value to be output.

The switch circuit 801 turns on (supply) and off (cut) the supply of the constant current output by the current power supply device 803. The switch circuit 801 is set or controlled to be on (output constant current) or off (cut off constant current) based on a signal from the control circuit 804. Typically, the switch circuit 801 is turned on before the start of the test and is maintained in the on state during the test of the bonding layer 105.

9, the current power supply device 803a and the current power supply device 803b are illustrated as one current power supply device each. The number of current power supply devices 803 is not limited to one. For example, two or more current power supply devices 803a and two or more current power supply devices 803b may be provided. As the number of current power supply devices 803a and current power supply devices 803b increases, a wider variety of waveforms of current Ia and current Ib or voltage waveforms can be generated.
In the embodiment of the present invention, the current power supply device 803 is described, but the current power supply device 803 is not limited to one that outputs a constant current.

For example, a current power supply device 803 capable of setting a maximum voltage is used. An example is a device that functions to output a predetermined constant current at a set maximum voltage under certain conditions. Another example is a device that is configured to set the output terminal voltage to a predetermined maximum voltage when outputting a constant current.

In the present invention, it goes without saying that the current power supply device 803 does not have to be a device that outputs only a constant current, but may be a power supply device that can output or set a voltage and a current.

In the embodiment of FIG. 9, a constant current is generated by the current power supply device 803, but a constant current can also be achieved by adjusting the applied voltage according to the resistance state of the thin film heater 117. Therefore, the present invention is not limited to the current power supply device 803 that outputs a current, and it goes without saying that it may be configured as a power supply device that outputs a voltage. It also goes without saying that it may be configured as a power supply device that outputs a current and a voltage.

The current power supply 803b supplies a constant current Ib to the thin-film heater 117. The thin-film heater 117 generates heat in response to the constant current Ib applied. The generated heat is transferred to the SiC substrate 106, heating the bonding layer 105. The SiC substrate 106 has high thermal conductivity. Meanwhile, the copper plate 104 is maintained at a constant temperature by the heating/cooling plate 101.

The upper side of the bonding layer 105 is heated by heat from the thin film heater 117 from the SiC substrate 106 side, and the lower side of the bonding layer 105 is maintained at a constant temperature by the copper plate 104. Therefore, temperature information ΔT is generated from the upper side to the lower side of the bonding layer 105. The radiation thermometer, infrared thermography camera 108, etc. mainly measure the temperature of the upper side of the bonding layer 105 and the temperature of the lower side of the bonding layer 105. The temperature difference is obtained as temperature information ΔT.

A constant current Ib is applied to the thin film heater 117, causing the thin film heater 117 to generate heat. A constant current Ia is applied to the temperature probe 116. The constant current Ia is a relatively small current, and the temperature probe 116 rarely or never generates heat at this constant current Ia. A constant current Ib is applied to the thin film heater 117, causing the thin film heater 117 to generate heat. The temperature probe 116 is heated. The relationship between the terminal voltage and temperature of the temperature probe 116 is obtained in advance.

When the temperature probe 116 is heated, the terminal voltage of the temperature probe 116 (measured by a voltmeter 122a) changes. The control circuit 804 acquires the terminal voltage and adjusts the constant current Ib flowing through the thin film heater 117 so that the SiC substrate 106 reaches a predetermined temperature. The constant current Ib is 0.2 A or more and 2 A or less. The constant current Ib is preferably set in increments of 1 mA or less.
In the above embodiment, the constant current Ib is adjusted by measuring the voltage between the terminals of the temperature probe 116 and adjusting the constant current Ib flowing through the thin film heater 117 .

The constant current Ib can also be set and adjusted by measuring the temperature of the SiC substrate 106 or the temperature of the bonding layer 105 with a radiation thermometer, an infrared thermography camera 108, or the like. The temperature information ΔT is measured with the infrared thermography camera 108, and the constant current Ib flowing through the thin film heater 117 is adjusted depending on whether the temperature information ΔT is a predetermined value or within a predetermined range.

It goes without saying that the constant current Ib flowing through the thin film heater 117 may be adjusted taking into consideration both the temperature information ΔT from the infrared thermography camera 108 or the like and the voltage between the terminals of the temperature probe 116 (measured by the voltmeter 122 a ).
The heat generation of the thin-film heater 117 may be adjusted or set by turning on and off the switch circuit 801b to turn on and off the constant current Ib flowing through the thin-film heater 117.

The heater chip 109 of the present invention is not limited to the configuration shown in FIG. 2, and a wide variety of configurations are exemplified. Examples include the configurations or structures shown in FIG. 7, FIG. 16, FIG. 17, FIG. 27, FIG. 34, FIG. 43, etc.

The substrate 106 of the heater chip 109 is made of SiC, AlN, or the like. A thin-film heater 117 is formed or arranged in a spiral or concentric shape on the surface of the substrate 106 in FIG. 7. Similarly, the temperature probe 116 is also formed or arranged in a spiral or concentric shape.

By configuring or forming the thin-film heater 117 in a spiral or concentric shape, the SiC substrate 106 and the like can be uniformly heated. A constant current Ib is applied to the terminal electrodes 115a and 115b of the thin-film heater 117.

A constant current Ib is applied to terminal electrodes 115a and 115b of the thin film heater 117. A constant current Ia is applied to terminal electrodes 114a and 114b of the temperature probe 116.

The thin-film heater 117 may be formed in a zigzag shape, a square shape, or a radial shape. It goes without saying that multiple thin-film heaters 117 may be formed or arranged on the heater chip 109. The above points also apply to the temperature probe 116.

Figure 9 shows an example in which one SiC substrate 106 and bonding layer 105 are arranged on one copper plate 104. However, the present invention is not limited to this.

Figure 10 shows an example in which one copper plate 104 is placed on the heating/cooling plate 101, and multiple bonding layers 105 are formed on the copper plate 104. Each bonding layer 105 is sandwiched between heater chips 109.

The bonding layer 105a is sandwiched between the heater chip 109a and the copper plate 104. The bonding layer 105b is sandwiched between the heater chip 109b and the copper plate 104. The bonding layer 105c is sandwiched between the heater chip 109c and the copper plate 104. The bonding layer 105d is sandwiched between the heater chip 109d and the copper plate 104. The bonding layer 105e is sandwiched between the heater chip 109e and the copper plate 104.

The temperatures of points A and B of each bonding layer 105 are measured by an infrared thermography camera 108 or the like. The infrared thermography camera 108 is placed on an XYZ stage 110, and moves on the XYZ stage 110 to obtain temperature information ΔT at points A and B of each bonding layer 105.

By varying the material or composition of each bonding layer 105 (bonding layers 105a to 105e), it is possible to simultaneously obtain various pieces of information about the bonding layers 105 (such as characteristics and life span).

By varying the temperature of the heater chip 109 for each bonding layer 105 (bonding layers 105a to 105e), it is possible to simultaneously obtain various pieces of information (characteristics, lifespan, etc.) about the bonding layers 105 for the temperature to which the bonding layers 105 are heated.

Although the temperature of the bonding layer 105 is measured using the infrared thermography camera 108, this is not limited to temperature. It goes without saying that any measurement device data can be used as long as the value or information is correlated or proportional to temperature.

Figure 11 is an explanatory diagram of the bonding layer evaluation method and bonding layer evaluation device of the present invention. A gold plating film 112c is formed between the Ni-P film 111d and the bonding layer 105, and a gold plating film 112a is formed between the Ni-P film 111a and the bonding layer 105. When the bonding layer 105 is formed, gold diffuses into the bonding layer 105, and the gold layer disappears, so it is not shown in the figure.

As shown in FIG. 11, when a constant current Ib is applied to the thin-film heater 117, the thin-film heater 117 generates heat, and the generated heat is transferred to the SiC substrate 106. The generated heat causes a diffusion portion 901 to occur in the bonding layer 105. In the diffusion portion 901, the heat causes the material and composition that constitute the bonding layer 105 to move or the characteristics to change. In addition, cracks occur, voids expand, flux and the like leak out, and the like. These changes or occurrences cause a change in the temperature state and temperature information ΔT of the bonding layer 105.

Depending on the structure or material of the bonding layer 105, a specific temperature information ΔT or a difference in temperature information ΔT occurs in the initial state (a state in which the bonding layer 105 is heated by the thin film heater 117 and reaches a predetermined temperature). The temperature information ΔT in the initial state can be used to quantitatively evaluate the bonding layer 105 or to grasp the characteristics of the bonding layer 105.

As described above, the present invention can quantitatively evaluate the bonding layer 105 or grasp the characteristics of the bonding layer 105 using temperature information ΔT in the initial state. In addition, the bonding layer 105 changes when it is heated or warmed. By acquiring temperature information ΔT, the state of change can be quantitatively measured, and the lifespan, characteristic deterioration state, or change over time can be quantitatively grasped.

The upper side of the bonding layer 105 is heated by the thin film heater 117. The copper plate 104 is maintained at a predetermined temperature by the heating/cooling plate 101. Therefore, a temperature distribution occurs from the top to the bottom of the bonding layer 105, and the temperature information ΔT changes from the top to the bottom of the bonding layer 105.

If the bonding layer 105 is formed uniformly, heat transfer is facilitated, the heat distribution is uniform, and the temperature information ΔT is also uniform. If cracks or voids occur in the bonding layer 105, heat transfer is reduced in the crack or void area. Therefore, the heat distribution is non-uniform, and the temperature information ΔT differs in each part of the bonding layer 105.

As shown in FIG. 12, the heat generated by the thin film heater 117 generates a temperature distribution in the bonding layer 105 as shown by the dotted line. The temperature distribution indicates the composition, structure, and material of the bonding layer 105.

As shown in FIG. 12, the temperatures at points A and B of the bonding layer 105 are measured by an infrared thermography camera 108. Temperature information ΔT is obtained from the temperatures at points A and B (temperature information ΔT). The state of the bonding layer 105 can be quantitatively grasped from the temperature information ΔT.

The bonding layer 105 can be quantitatively evaluated by acquiring temperature information ΔT at multiple points with an infrared thermography camera 108 and determining temperature information ΔT between multiple points on the bonding layer 105. In addition, the life or deterioration of the bonding layer 105 can be quantitatively measured by heating or overheating the bonding layer 105 and comparing the temperature information ΔT after a specified time has elapsed with the temperature information ΔT in the initial state.

In FIG. 12, temperature information ΔT at points A and B is measured using a radiation thermometer, infrared thermography camera 108, etc. To measure or understand the characteristics, structure, life, etc. of the bonding layer 105 in detail, temperature information ΔT is obtained at three or more points as shown in FIG. 13.

In Fig. 13, nine measurement points are measured at equal intervals (d/2), where d is approximately the thickness of the bonding layer 105. As shown in Fig. 13, temperature information ΔT is acquired in a matrix form for the bonding layer 105. Temperature information ΔT between each point is calculated from the acquired temperature information ΔT at each point.
The temperature information ΔT is correlated with the failure rate. Fig. 14 is an explanatory diagram that shows a schematic diagram of the relationship between the temperature information ΔT and the failure rate.

When the temperature information ΔT is small, the bonding layer 105 is uniform and no or few voids or cracks have occurred. When the temperature information ΔT is large or non-uniform, the bonding layer 105 often has non-uniform material mixture, voids, cracks, etc.

14, when the temperature information ΔT is ΔT1 or less, the failure rate is below a certain level up to F1. However, when the temperature information ΔT is ΔT1 or more, the failure rate increases suddenly when ΔT1 is exceeded.
If it is necessary to keep the failure rate of the bonding layer 105 below a predetermined failure rate F2, the temperature information ΔT must be set to ΔT2 or less.

By producing each bonding layer 105 and acquiring temperature information ΔT using an infrared thermography camera 108, the bonding layer 105 can be quantitatively evaluated and the failure rate can be determined. In addition, by overheating the bonding layer 105 using a thin-film heater 117, the life and deterioration of the bonding layer 105 can be quantitatively measured or determined, and the failure rate can be predicted.

The graph in Figure 14 is created by measuring or acquiring the temperature information ΔT and the failure rate of the sample of the produced bonding layer 105. By creating the graph and acquiring the temperature information ΔT of the newly produced bonding layer 105 with an infrared thermography camera 108 or the like, the failure rate can be quantitatively predicted.

Figure 15 shows a thermal simulation of the state in which the bonding layer 105 is heated by the thin-film heater 117. The thin-film heater 117 generates a temperature distribution in the bonding layer 105.

Thermal simulation can be realized by setting at least one of the following pieces of information: the thickness and position of the Ni-P film 111, the thickness and position of the thin-film heater 117, the shape and position of the heater chip 109, the current applied to the heater chip 109, the shape and position of the temperature probe 116, and the material or composition and thickness of the bonding layer 105.

The temperature information ΔT at points A, C, and B obtained by the infrared thermography camera 108 can also be obtained by thermal simulation. A correlation can be established between the thermal simulation values and the values measured by the infrared thermography camera 108.

As shown in FIG. 9, the infrared thermography camera 108 acquires temperature information ΔT of the end surface of the bonding layer 105. The acquired temperature information ΔT is used to vary or set the constant current Ib applied to the thin-film heater 117.

It is preferable to synchronize the measurement of the infrared thermography camera 108 with the varying constant current Ib. The measurement of the infrared thermography camera 108 is performed in synchronization with the timing at which the constant current Ib is varied. It is also preferable to synchronize the measurement of the terminal voltage of the temperature probe 116 with the varying constant current Ib.

As shown in Figures 9 and 8, the constant current Ib to be applied to the thin-film heater 117 is preferably set by acquiring temperature information ΔT at a point D in the center of the bonding layer 105, which is a position (depth direction) away from the end face by a distance t, and setting the constant current Ib using the temperature information ΔT at the point D in the center.

The temperature information ΔT at the central point D cannot be measured directly. In the present invention, a thermal simulation is performed as shown in FIG. 15, and temperature information ΔT at points A, B, and C is obtained by thermal simulation in the layer below point D, which is a distance t away from the end face b1 as shown in FIG. 8.

By carrying out a thermal simulation, for example, Figure 8 (b1) shows the temperature distribution state obtained by thermal simulation on line b1, Figure 8 (b2) shows the temperature distribution state obtained by thermal simulation on line b2, and Figure 8 (b3) shows the temperature distribution state obtained by thermal simulation on line b3.

In addition, the temperature distribution state of lines b2 and b3 can be obtained by thermal simulation using temperature information ΔT obtained by an infrared thermography camera as the temperature distribution information on line b1. In this case, since the thermal simulation is based on actual measured values, the temperature distribution state of lines b1 and b3 can be obtained more accurately.

The present invention obtains temperature information ΔT at the center or any other location of the bonding layer 105 through thermal simulation, and controls the constant current Ib of the thin-film heater 117 based on the obtained temperature information ΔT. Therefore, temperature control can be performed with high precision.

Although the thin-film heater 117 and the temperature probe 116 are formed on the upper surface of the base substrate 106, this is not limiting. For example, they may be formed on the surface of the base substrate 106 that contacts the bonding layer 105. For example, at least one of the thin-film heater 117 and the temperature probe 116 may be formed between the Ni-P film 111d and the base substrate 106. In the case of this configuration, the thin-film heater 117 etc. is formed on the lower surface of the base substrate 106, an insulating film such as SiO ₂ is formed on the thin-film heater 117 etc., and the Ni-P film 111d is formed thereon.

A Ni-P film 111a is formed on the copper plate 104, and a Ni-P film 111d is formed on the base substrate 106. The Ni-P film 111 is assumed to be an electrode or metal layer (metal film) for the bonding layer 105. The Ni-P film 111 is formed to improve adhesion with the bonding layer 105.

It goes without saying that an appropriate material can be selected at the appropriate time depending on the type of bonding layer 105. For example, when the bonding layer 105 is solder, nickel (Ni), tin, lead, etc. are exemplified. When the bonding layer 105 is an organic material such as epoxy resin, a primer for epoxy resin is exemplified. In this case, the epoxy resin primer 111 functions as a contact layer (contact layer) rather than an electrode.

In this specification and the drawings, the base substrate 106 is described as a substrate, but is not limited to this. The base substrate 106 may be a film, such as a base film 106. Any configuration is acceptable as long as the member has at least a heat generating material such as a thin film heater 117 and an intermediate layer 111d for bonding.

Although the present specification and drawings refer to the copper plate 104, the copper plate 104 is not limited to a plate. The plate may be a film or a sheet. It goes without saying that the plate may also be a solid component with some thickness. The copper plate 104 may have any configuration as long as it has an intermediate layer 111a for bonding on one side.

The thin film heater 117 and the temperature probe 116 are not limited to being thin films. Needless to say, they may be made of wire or the like and have a certain thickness. Examples of the thin film heater 117 include a sheet heating element heater, a ceramic heater, a film heater, a sheet light-emitting carbon, and a heater made of a Peltier element.
The heater may be any type of heating means. It goes without saying that the temperature probe 116 may be a thermocouple, a radiation thermometer, or the like.

In this specification, the heating/cooling plate 101 is placed on the back surface of the copper plate 104, and the copper plate 104 is maintained at a predetermined temperature, but this is not limited to the above. For example, a Ni-P film 111a may be formed directly on the surface of the heating/cooling plate 101, and a bonding layer 105 may be placed between the Ni-P film 111a and the Ni-P film 111d of the SiC substrate 106.

One of the functions of the copper plate 104 is to maintain one side of the bonding layer 105 at a uniform, predetermined temperature. Therefore, the copper plate 104 is not limited to metal. For example, a plate or sheet with high thermal conductivity such as AlN, SiC, or ceramic can be used. The plate 104 has an area at least equal to or greater than the contact area with the bonding layer 105, and is a member that has a uniform thermal conductivity in that area.

The polyimide sheet 107 is not limited to a sheet. A plate-shaped resin member may be attached to the bonding layer 105 with an adhesive or the like. Also, an acrylic or epoxy resin may be applied. Also, it is not limited to polyimide, and a precursor polyamide or the like may be used.

As an example of a means for measuring or acquiring temperature, an infrared thermography camera 108 is shown. However, any device that can measure the temperature of the bonding layer 105 and its vicinity in a non-contact manner can be used. For example, a radiation thermometer is an example.

Figure 16 shows a plan view (Figure 16(a) and Figure 16(b)) and a cross-sectional view (Figure 16(c)) of a heater chip 109 in another embodiment of the present invention. Note that Figure 16(c) is a cross-sectional view taken along line AA' in Figure 16(a) or Figure 16(b).

The difference from FIG. 2 etc. is that the thickness of the thin film heater 117 is made thinner than that of the terminal electrode 115, and the resistance value of the thin film heater 117 is made higher. The thin film heater 117 is made of electroless Ni-P. The electroless Ni-P is thick in the portion a of the thin film heater 117 (below the terminal electrode 115), and is thin in the portion b of the thin film heater 117 (the portion that mainly contributes to heat generation). The electroless Ni-P film is formed to be thinner at least in the portion b than in the portion a. The resistance value is increased by forming the film thickness of the portion b thinner. Therefore, when a constant current is applied to the thin film heater 117, the high resistance value of the portion b allows the heat generation of the portion b to be increased.
16B, the thickness of the width L1 portion may be different from that of the width L2 portion. By making the thickness of the width L2 portion thinner than that of the width L1 portion, the heat generation in the width L2 portion becomes larger.

The following explanations of Figs. 16 and 17 will focus on the differences with other drawings and specifications. Therefore, it goes without saying that the descriptions or contents of this specification and drawings can be reused or combined with the descriptions or contents of Figs. 16, 17, etc.

The above points also apply to the specification and drawings of the present invention. The points described in the specification and drawings of the present invention may be mutually reused, combined, or substituted.

The heater chip 109 shown in FIG. 16(a) has a thin-film heater 117 formed with a width L1 and a thickness b. The electroless Ni-P corresponding to the thickness a is the terminal portion, and a terminal electrode (gold plating film) 115 is formed on the surface.

The heater chip 109 shown in FIG. 16(b) has a thin-film heater 117 formed with a portion of width L1 and a portion of width L2. The width L2 of the thin-film heater 117 is formed narrower than the width L1. By making the width L2 portion narrower than the width L1 portion, the resistance value of the width L2 portion becomes higher, and heat can be concentrated in the width L2 portion.

The thin film heater 117 is formed with a thickness b. The electroless Ni-P corresponding to the thickness a is the terminal portion, and a terminal electrode (gold plating film) 115 is formed on the surface.

16B, when a constant current is applied between the terminal electrodes 115a and 115b, the resistance value is high in the width L2 portion, so heat generation in the width L2 portion is large. Therefore, heat generation in the width L2 portion of the thin film heater 117 of the heater chip 109 is large, and the heating or overheating state of the bonding layer 105 of the sample below the width L2 portion is favorable.
16, there is one thin film heater 117 between the terminal electrodes 115a and 115b, but the present invention is not limited to this.
As shown in FIGS. 17A and 17B, a plurality of thin film heaters 117 may be formed or disposed between the terminal electrodes 115a and 115b.

In addition, in FIG. 17(b), the width of the thin-film heater 117 has two stages (width L1, width L2), but as shown in FIG. 17(b), it may have three stages (width L1, width L2, width L3) or more. In the case of constant current drive, the amount of current flowing per unit wiring width is large in the narrow part of the thin-film heater 117. Therefore, the amount of heat generated in the narrow part is large. In FIG. 17(b), the bonding layer 105 of the sample below the width L3 part is well heated.

In FIG. 17(a), two thin film heaters, 117a and 117b, are formed or placed between terminal electrodes 115a and 115b. Thin film heater 117 has a portion with width L1 and a portion with width L2. The portion with width L1 is short in length. It is also placed near terminal electrode 115. The portion with width L1 is formed to prevent current flowing from terminal electrode 115 into the portion with width L2 of thin film heater 117 from concentrating.

In FIG. 17, two thin film heaters 117a and 117b are formed or arranged between terminal electrodes 115a and 115b, but this is not limited to this. Needless to say, three or more heaters may be used.

In FIG. 17(b), two thin film heaters, 117a and 117b, are formed or placed between terminal electrodes 115a and 115b. Thin film heater 117 has a portion with width L1 and portions with widths L2 and L3. The portion with width L1 is short. It is also placed near terminal electrode 115. The portion with width L1 is formed to avoid concentration of current flowing from terminal electrode 115 to the portion with width L2 of thin film heater 117.

The width is not limited to three stages, namely, the portion of width L1, the portion of width L2, and the portion of width L3, but may be four stages or more. It goes without saying that the width may also be changed smoothly. For example, it may be formed so that the width changes in a curved line.

The portion of width L3 is formed narrower than the portion of width L2. Therefore, in the case of constant current driving, the amount of current flowing per unit wiring width is large in the narrow portion of the thin film heater 117. Therefore, the heat generation is the largest in the portion of width L3, and the bonding layer 105 of the sample below the portion of width L3 is well heated.
Needless to say, the above matters regarding the shape etc. of the thin film heater 117 can also be applied to the temperature probe 116 .
Hereinafter, a method for producing the heater chip 109 of the present invention shown in FIGS. 16, 17, etc. will be described with reference to the drawings.

In Figures 18, 19, 20, and 21, the left side of each figure shows a side view of the heater chip, and the left side of each figure shows a plan view of the heater chip 109.

Figures 18(a1) and 18(a2) show a SiC substrate 106. As explained in Figures 2, 5, 6, etc., this is not limited to a SiC substrate. The substrate 106 may be made of GaN. Also, the explanation or description in Figure 18 etc. focuses on the thin film heater 117, but it goes without saying that it can also be applied to the temperature probe 116, as in Figure 2 etc.

The matters described in the explanations of Figures 18, 19, 20, 21, and 22 will be explained with a focus on the differences with other drawings and specifications. Therefore, it goes without saying that the matters explained or described below can be reused or combined as appropriate. They can also be combined with similar configurations or modifications. It goes without saying that the matters described in Figures 18, 19, 20, 21, and 22 can also be applied to other embodiments of this specification and drawings.

As shown in Fig. 18(b1) and Fig. 18(b2), a mask 501a is applied to the front surface of the SiC substrate 106. Similarly, a mask 501b is applied to the rear surface of the SiC substrate 106. The mask 501 preferably contains an alkali-soluble acrylic polymer.

Next, the surface of the SiC substrate 106 is roughened using a femtosecond laser device (not shown) (FIGS. 18(c1) and 18(c2)). Femtosecond laser light 502 or picosecond laser light 502 is irradiated to roughen the portions of the surface of the SiC substrate 106 that correspond to the thin-film heater 117 and the terminal electrode 115. FIG. 18(c1) is a cross-sectional view taken along line AA' in FIG. 18(c2).

By irradiating the femtosecond laser light 502, etc., the positions of the SiC substrate 106 where the terminal electrodes 115 and thin film heaters 117 are to be formed are roughened (roughened), forming roughened surfaces 119a.

Since femtosecond green lasers are second harmonic waves, they can produce relatively high output, and the irradiated laser light is well absorbed by the SiC substrate 106.

The wavelength of the light emitted by the femtosecond green laser is preferably 500 nm to 530 nm. The pulse width is preferably 1 femtosecond to 1000 femtoseconds.

When using a picosecond laser, the wavelength of the light emitted by the picosecond laser is preferably 500 nm to 530 nm. The pulse width is preferably 1 picosecond to 10 picoseconds.

The surface of the SiC substrate 106 is roughened by a picosecond laser beam having a pulse width in picoseconds or a femtosecond laser beam having a pulse width in femtoseconds. The roughened surface has an arithmetic mean roughness Ra of 0.2 μm or more. The arithmetic mean roughness Ra is preferably 0.3 μm or more, 0.4 μm or more, and 0.5 μm or more in that order.

A femtosecond laser device generally generates femtosecond laser light 502 with a pulse width of subpicoseconds to tens of femtoseconds. When an ultrashort pulse of laser light 502 of subpicoseconds to tens of femtoseconds is irradiated onto a material, the pulse width is sufficiently short compared to the thermal diffusion characteristic time of the material, so that light energy can be effectively input to the irradiated area.

Even narrow areas, such as width L3 in Figure 17(b), can be roughened well. In addition, widths such as widths L1, L2, and L3 can be easily and stably roughened.

The femtosecond laser beam 502 can limit the thermal effect on the periphery of the irradiation, realizing high-precision microfabrication. In addition, since the electric field strength of the laser beam is very high, it can spatially selectively induce nonlinear effects such as multiphoton absorption and multiphoton ionization only in the area where the beam is focused.
By irradiating a pulse of femtosecond laser light 502, the portions of the mask 501 corresponding to the portions where the thin film heaters 117 and the like are to be formed are removed, and recesses are formed.

Patterning of wiring (thin film heater 117, temperature probe 116, etc.) may be performed based on marks formed on the surface of mask 501. Positioning is performed based on cross marks 130 (not shown) etc. formed on SiC substrate 106. Cross marks 130 etc. are provided in at least two diagonal positions.

The cross mark 130 formed on the SiC substrate 106 is captured by a camera, the cross mark 130 is image-recognized, the position of the cross mark 130 is compared with the design coordinates, and the patterning (thin film heater 117, temperature probe 116, etc.) position (the location where the laser light is irradiated) is positioned, and the laser light 502 is irradiated.

Similarly, as shown in Fig. 18(d1) and Fig. 18(d2), the rear surface of the SiC substrate 106 is also irradiated with femtosecond laser light 502 and roughened (roughened). A roughened surface 119 is also formed on the rear surface of the SiC substrate 106.

A nickel-phosphorus (Ni-P) film 111 is also formed on the back surface of the SiC substrate 106. Therefore, the portion of the SiC substrate 106 where the Ni-P film 111 is to be formed is also roughened by the femtosecond laser light 502.
Fig. 18(d1) is a cross-sectional view taken along line AA' in Fig. 18(d2). Note that the cross-sectional positions of the cross-sectional views are the same in the other drawings.

Next, as shown in Fig. 19(e1) and Fig. 19(e2), a masking tape 120b is attached to the back surface of the SiC substrate 106. An example of the masking tape 120 is Nitto Denko N-300.

Masking tape 120 is used to prevent the infiltration of plating solution. Therefore, any material that can prevent the infiltration of plating solution and can be peeled off after prevention is complete may be used. For example, a masking tape made by applying a liquid made of unpolymerized polyimide and then hardening the liquid made of polyimide may be used in place of masking tape 120.

As shown in FIG. 18(e2), the surface of the SiC substrate 106 is roughened by irradiation with laser light in the areas where the terminal electrodes 115 and thin-film heaters 117 are to be formed. In the other areas, the mask 501a remains.

As described above, the roughening using the femtosecond laser light 502 is also performed on the areas corresponding to the terminal electrodes 114 and 115. A Ni-P film 111 is formed on the roughened areas.

The terminal electrode 115 has a large roughened area. The thin-film heater 117 has a narrow roughened line width. It is preferable to change the roughened state of the thin-film heater 117 depending on the roughened area so that the thin-film heater 117 is roughened more (the unevenness caused by the roughening is deepened). The arithmetic mean roughness Ra is made different based on the roughened area.
For example, in FIG. 16B and FIG. 17B, the roughened state or the arithmetic mean roughness Ra may be made different between widths L1, L2, and L3.

For example, as shown in Fig. 16B, the arithmetic mean roughness Ra is made different between the portion of line width L1 and the portion of line width L2. As shown in Fig. 17, the arithmetic mean roughness Ra is made different between the portion of line width L1 and the portion of line width L2 or the portion of line width L3.
The roughening state can be easily varied by changing or setting the laser intensity of the femtosecond laser light 502 and the moving speed of the irradiated laser pulse.

The SiC substrate 106 is degreased using an acidic degreaser at 45°C for 5 minutes, for example. A pre-dip process is performed using a hydrochloric acid aqueous solution. The retention time is, for example, 2 minutes.

Next, as shown in FIG. 19(f1) and FIG. 19(f2), a tin-lead (Sn--Pd) catalyst 504 is applied, coated or formed on the roughened surface 119 and the surface of the remaining portion of the mask 501a.
The Sn--Pd catalyst 504 is a colloidal particle, and a Sn-rich layer and a Sn2+ layer are formed in this order on the surface of the Sn--Pd core.

By immersing the SiC substrate 106 with the Sn-Pd catalyst 504 in a hydrochloric acid solution, the Sn layer is removed and the internal Pd catalyst is exposed. Since the Pd catalyst is exposed, a reaction occurs in the electroless Ni-P plating solution (described later) in the area where the Sn-Pd catalyst 504 is present.

Next, as shown in Fig. 19(g1) and Fig. 19(g2), the mask 501a is peeled off using an alkaline solution. As shown in Fig. 19(g1), the Sn-Pd catalyst 504a is not present in the portion of the SiC substrate 106 where the mask 501 has been peeled off.
Next, as shown in FIG. 19(h1) and FIG. 19(h2), electroless Ni--P plating is performed on the surface of the SiC substrate 106 to form a thin-film heater 117.
As the electroless Ni-P plating solution, a reduction precipitation type electroless Ni-P plating solution that operates in an acidic to neutral range and uses sodium hypophosphite as a reducing agent can be used.

As the chelating agent, malic acid, citric acid, malonic acid, tartaric acid, and other oxycarboxylic acids, acetic acid, succinic acid, and other monocarboxylic acids, and ammonia, glycine, and other amines can be used alone or in combination.

Pd is added to act as a catalyst so that the reducing agent in the electroless Ni-P plating solution releases electrons on the SiC substrate 106. The Ni ions in the electroless Ni plating solution are reduced by the electrons released by the oxidation reaction of the reducing agent, and are precipitated on the surface of the SiC substrate 106, forming the thin-film heater 117 and terminal electrode.

Although the temperature probe 116 is not shown in Figs. 16 and 17, it goes without saying that the heater chip 109 of the present invention in Figs. 16 and 17 may be equipped with a temperature probe 116. It also goes without saying that the matters described above in Figs. 16 and 17 can be applied not only to the thin-film heater 117 but also to the temperature probe 116. The above matters also apply to the following descriptions and drawings.

According to this embodiment, the roughened surface 119 is formed by the picosecond laser light 502 or the femtosecond laser light 502. By forming the roughened surface 119, Ni-P plating with good adhesion can be easily performed on the SiC substrate 106, which is made of a material that is difficult to plate, without using special chemicals or photolithography techniques.

In this embodiment, a mask 501a is used to leave Sn-Pd catalyst 504a on the roughened surface 119 of the SiC substrate 106 that corresponds to the thin-film heater 117 and the terminal electrode portion. A plating film is formed on the Sn-Pd catalyst 504a. Therefore, the thin-film heater 117 is patterned with good accuracy, and surface polishing is not required.

In this embodiment, the plating pattern is formed while the areas other than those corresponding to the wiring pattern are protected by the mask 501a. Therefore, electroless Ni-P plating is performed only on the roughened areas, so that a thin-film heater 117, etc., can be formed to the desired thickness.

Next, as shown in FIG. 20(i1) and FIG. 20(i2), masking tape 120a is formed or placed around the area where thin-film heater 117 is to be formed. Masking tape 120a is not formed or placed on the area where terminal electrode 115 is to be formed.

As shown in Figures 20(j1) and 20(j2), similar to Figures 19(h1) and 19(h2), electroless Ni-P plating is performed on the surface of the SiC substrate 106, and an electroless Ni-P plating film is formed on the terminal electrode 115.

The electroless Ni-P plating solution used is the electroless Ni-P plating solution shown in Fig. 19 (h1) and Fig. 19 (h2). The same applies to the chelating agent, etc., so the explanation is omitted.

As shown in FIG. 20(j1), the thin film heater 117 is formed with an electroless Ni-P plating film 111a. The terminal electrode 115 is formed by laminating the electroless Ni-P plating film 111a and the electroless Ni-P plating film 111b.

Therefore, the terminal electrode 115 has a lower resistance than the thin-film heater 117. Because the terminal electrode 115 has a low resistance, it does not generate heat even when a specified constant current is applied to it. Because the thin-film heater 117 has a high resistance, it generates heat well when a specified constant current is applied to it.

As shown in Figures 20(k1) and 20(k2), a substituted Au film (terminal electrode 115) is formed on the terminal electrode portion. A gold plating film 115 is formed on the surface of the Ni-P film 111a in a location corresponding to the terminal electrode.

As shown in Figures 20(l1) and 20(l2), the masking tape 120a is peeled off. By peeling off the masking tape 120a, the Ni-P plating film 111a serving as the thin-film heater is exposed.

Through the above steps, the terminal electrode 115 and the thin-film heater 117 are formed on the SiC substrate 106. Next, a process is carried out to form a Ni-P film 111c on the back surface of the SiC substrate 106.

As shown in Figures 21(m1) and 21(m2), a masking tape 120c is placed or formed on the Ni-P plating film 111a serving as the terminal electrode 115 and the thin-film heater 117. A coating agent is also applied.

As shown in Figures 21(n1) and 21(n2), the Sn-Pd catalyst 504b is applied, coated or formed on the surface of the roughened surface 119b. The Sn-Pd catalyst 504b is a colloidal particle, and a Sn-rich layer and a Sn2+ layer are formed in that order on the surface of the Pd-Sn core.

By immersing the SiC substrate 106 with the Sn-Pd catalyst 504b in a hydrochloric acid solution, the Sn layer is removed and the internal lead (Pd) catalyst is exposed. Since the Pd catalyst is exposed, a reaction occurs with the electroless Cu plating solution in the areas where the Sn-Pd catalyst 504b is present.

21(o1) and 21(o2), an electroless Ni-P plating film 111c is formed on the back surface of the SiC substrate 106. In addition, a gold plating film 112 is formed on the electroless Ni-P plating film 111c.
Next, as shown in FIG. 21(p1) and FIG. 21(p2), the masking tape 120c is peeled off, and the heater chip 109 is completed.

Figure 22 is an explanatory diagram of the configuration of a bonding layer evaluation device in another embodiment of the present invention. Figures 22(c1) and 22(c2) show a heater chip 109. A Ni-P plating film 111c is formed on the back surface of the heater chip 109, and a gold plating film 112 is formed on the surface of the Ni-P plating film 111c, but these are omitted to avoid complicating the drawing.

22(c2), solder 123 for electrically connecting the lead wire 121 is formed or disposed on the terminal electrode 115. Note that this is not limited to solder 123, and any configuration, material, etc. may be used as long as it is conductive and allows electrical connection between the lead wire 121 and the terminal electrode 115. For example, a configuration in which connection is made with a bonding wire is exemplified, and a configuration and material in which connection is made with anisotropic resin (ACF) is exemplified.
As shown in FIG. 22(a), a bonding layer 105 such as solder is disposed or formed between an oxygen-free copper plate 104a and an oxygen-free copper plate 104b.
In the oxygen-free copper plate 104, a Ni--P film 111 and a gold plating film 112 are formed on the surface in contact with the bonding layer 105, but these are not shown in the drawing to avoid complicating the drawing.

A Ni--P film 111 is formed on the surface of the oxygen-free copper plate 104b, and a gold plating film 112 is formed on the Ni--P film 111. A bonding layer 105 is disposed between the two gold plating films 112. When the bonding layer 105 is made of solder, the gold plating film 112 diffuses into the solder.
The oxygen-free copper plate 104 a mainly functions as a heat sink, and the oxygen-free copper plate 104 b has a function of transmitting heat from the heater chip 109 to the bonding layer 105 .

The oxygen-free copper plate 104 may be made of a material other than copper, so long as the material has good thermal conductivity. Examples include a ceramic plate, a stainless steel plate, a nickel plate, and a silver plate. For ease of explanation and understanding, this specification will be described as an oxygen-free copper plate 104.

The oxygen-free copper plate 104 is, for example, a copper plate having a thickness of 0.1 mm to 2 mm. A Ni-P film 111 is formed on the surface of the oxygen-free copper plate 104a. The Ni-P film 111 may be formed on the entire surface of the oxygen-free copper plate 104a, or may be formed specifically in an area or range where the heater chip 109 is to be mounted.
As shown in FIG. 22B, heat dissipating (heat conducting) grease 118 is applied or placed on the oxygen-free copper plate 104b.

The heat dissipation (heat transfer) grease 118 is based on a modified silicon-based grease that has little change in viscosity from room temperature to a relatively high temperature. It is preferable to use this heat dissipation (heat transfer) grease mixed with metal or metal oxide particles (filler) that have high thermal conductivity.

The main particles used are copper, silver, aluminum, etc., but also alumina, magnesium oxide, aluminum nitride, etc. These elements or mixtures are dispersed using a dispersion method appropriate for their particle diameter.

It is also preferable to use sintered silver (Ag) paste on the oxygen-free copper plate 104b. An example of the sintered silver paste is the MDot series (MDot-S5171) from Mitsuboshi Belting. MDot-S5171 has a high thermal conductivity of 15 W/m·K or more.
The thermal conductivity of the sintered paste is preferably 4 W/m·K or more. In addition to the sintered Ag paste, a sintered copper (Cu) paste may be used.

Sintered paste has the advantage that it has better thermal conductivity than heat dissipation (heat transfer) grease and can reduce the temperature of the heater chip 109. For example, in the case of heat dissipation (heat transfer) grease, when the solder layer is heated to 200°C, the heat resistance of the heat dissipation (heat transfer) grease and the heat resistance of the solder part of the wiring may be insufficient. In the case of sintered paste, this problem does not occur. Or, its occurrence is suppressed.

In FIG. 22(b), sintered Ag paste 118, etc. is placed on oxygen-free copper plate 104a, but it goes without saying that sintered Ag paste 118, etc. may be applied to the back surface of heater chip 109 to bond oxygen-free copper plate 104b and heater chip 109.

As shown in FIG. 22(c3), the heater chip 109 of FIG. 22(c2) is placed on the discharge grease or sintering paste 118 placed on the oxygen-free copper plate 104b. For example, if 108 is sintering paste, it is sintered at a low temperature, for example, at 200°C for 60 minutes. The sintering thermally connects the heater chip 109 and the oxygen-free copper plate 104b.

The bonding layer 105 is, for example, a solder sheet. By heating, it becomes the bonding layer 105 made of solder. The solder sheet is placed on the oxygen-free copper plate 104b. Solder paste may be used instead of the solder sheet.

As shown in FIG. 22(d), the heater chip 109 and the oxygen-free copper plate 104b are bonded by a bonding layer 105. As shown in FIG. 22(d), the heater chip 109, the oxygen-free copper plate 104b, and the bonding layer 105 are simultaneously polished and their edges are polished. The bonding layer 105 is mirror-finished by the edge polishing. If necessary, the bonding layer 105 is subjected to CP processing.

As shown in FIG. 22(d), a polyimide film 107 is attached to the polished surface. Alternatively, a photosensitive polyimide film is formed on the surface of the bonding layer 105. The photosensitive polyimide film is formed on the polished surface by a spin coating method, a slit coating method, a screen printing method, an inkjet spraying method, a spray coating method, a die coating method, a doctor knife coating method, a flexographic printing method, or the like. The area where the photosensitive polyimide film is formed includes at least the bonding layer 105.

22E, a lead wire 121 is attached via solder 123 on the terminal electrode 115. A current power supply device 803 is connected to the lead wire 121, and a constant current or the like is applied to the thin film heater 117.
The infrared thermography camera 108 measures the two-dimensional temperature distribution of the bonding layer 105 through the polyimide film 107 .

The bonding layer 105 is not limited to a bonding layer made of solder or the like. For example, it goes without saying that it can also be applied to a bonding layer (connection portion) bonded with silver paste or copper paste, a bonding layer (connection portion) made of sintered Ag paste, a connection portion such as a bonding wire, a connection portion made by electric discharge machining, a bonding layer (connection portion) made by high-frequency induction heating, and a fusion portion (connection portion) made by electromagnetic induction heating.

It goes without saying that this can also be applied to bonding surfaces where organic or inorganic materials are pressed or brought into contact with each other. Layers made of insulating or dielectric materials are also bonding layers (connecting parts).

The temperature information of the connection part can be measured using temperature information ΔT by an infrared thermography camera 108 or the like. Another example is a lock-in infrared thermography camera that measures temperature using a lock-in signal.

An example of a bonding layer evaluation method using the bonding layer evaluation device of the present invention is described below. A SiC heater chip 109 (having a thin-film heater 117 on the front surface and an Ag layer (sintered Ag paste, etc.) on the back surface) was used as the heat source. The back surface of the heater chip 109 and the oxygen-free copper plate 104 were treated with an electroless Ni-P film 111/substitutional gold plating film 112, and the heater chip 109 was soldered onto the oxygen-free copper plate 104 to prepare a sample.

At this time, a double-sided copper-clad substrate with electroless Ni-P film 111/substitutional gold plating film 112 treatment was also soldered near the heater chip 109. The solder composition was Sn-0.7Cu solder, and the thickness of the solder sheet used was 100 μm.

Soldering was performed by atmospheric pressure reflow (peak temperature 250°C 10 sec), and the sample used had a solder thickness of 100±20 μm between the heater chip 109 and oxygen-free copper plate 104 after soldering.

After the end faces of the sample were mirror-finished, the thin film heater 117 of the heater chip 109 was connected to the double-sided copper-clad plate described above by Au wire bonding (φ25 μm), and the sample was placed on the heating and cooling plate 101.

The Ni-P film 111d and Ni-P film 111a in contact with the bonding layer 105 and the bonding layer 105 are polished or planarized. By polishing or planarizing, the bonding layer 105 and the surrounding area become flat and have a mirror surface. By making them flat and mirror-like, the amount of infrared radiation radiated from the bonding layer 105 and the like can be well correlated with the temperature of the bonding layer 105. This improves the accuracy of temperature measurements by the infrared thermography camera 108.

Thereafter, a direct current was applied from a current power supply device 803b to the thin film heater 117 formed or disposed on the surface of the heater chip 109, causing the heater chip 109 to generate heat.
This created a temperature gradient in the solder joint layer, with the rear surface of the heater chip 109 being the hot side (heating side) and the copper plate 104 side being the cold side (cooling side).

In order to visualize the generated temperature gradient, the mirror-finished surface of the sample was observed with an infrared thermography camera 108, and the temperature gradient was determined from the temperature difference between the Ni-P film 111 layer on the back surface of the heater chip 109 (hot side Ni-P film 111 layer) and the Ni-P film 111 layer on the copper plate 104 side (cold side Ni-P film 111 layer).
In order to ensure the emissivity of the cross section, a polyimide tape was attached and the temperature was measured by the infrared thermography camera 108.

When the temperature on the backside of the heater chip 109 was 200°C and the temperature of the copper plate 104 was about 145°C, the temperature gradient between the Ni-P film 111 layers on the hot and cold sides was 2571°C/cm.

A TM (thermomigration) test was carried out under these conditions. The TM (thermomigration) test time was 5 hours. Furthermore, in order to understand the effects of the presence or absence of a temperature gradient, samples were also prepared for a 200°C storage test in which they were kept in a thermostatic chamber set at 200°C for 5 hours, as a condition in which a temperature gradient was not intentionally created.

After the TM (thermomigra- tion) test and the 200°C storage test, the end faces of the samples were mirror-finished again, and the solder joint layer was observed by cross-sectional SEM observation. At that time, the composition of the solder joint layer was analyzed by energy dispersive X-ray spectroscopy (EDS). Furthermore, the distribution of Ni in the solder joint layer before and after each test was investigated by EDS.

Initially, it was confirmed that an alloy layer (Cu, Ni) ₆ Sn ₅ was formed on both the back surface of the chip and the Ni-P film 111 layer on the copper plate 104 side. After the 200°C storage test, the alloy layer on the back surface of the chip changed to (Ni, Cu) ₃ Sn ₄ , and on the copper plate 104 side, (Ni, Cu) ₃ Sn ₄ was formed under the (Cu, Ni) ₆ Sn ₅ layer. This is presumed to be due to a decrease in the Cu concentration in the solder accompanying the growth of the (Cu, Ni) ₆ Sn ₅ layer.

After the TM (thermomigra- tion) test, it was found that the Ni-P film 111 layer on the back surface of the heater chip 109 (hot side) had disappeared. In addition, the Ni-P film 111 layer on the copper plate 104 side (cold side) showed growth of a P-rich layer, formation of vertical voids, and thinning of the Ni-P film 111 layer, but the Ni-P film 111 layer itself remained.

From this, it became clear that when the temperature of the hot-side Ni-P film 111 layer is set to 200°C in a TM (thermomigra- tion) test and a temperature gradient of about 2000-3000°C/cm is generated between the Ni-P film 111 layers, the hot-side Ni-P film 111 layer disappears.

Furthermore, initially, an alloy layer (Cu, Ni) ₆ Sn ₅ was formed on the Ni-P film 111 layer on the rear surface of the heater chip 109, but after the TM (thermomigrations) test, no alloy layer was confirmed on the Ni-P film 111 layer on the rear surface of the heater chip 109. In contrast, after the TM (thermomigrations) test, (Ni, Cu) ₃ Sn ₄ was formed with a thickness of about 10-30 μm on the Ni-P film 111 layer on the copper plate 104 side.
From these findings, it appears that there is a difference in the Ni distribution after the 200° C. storage test and after the TM (thermomigrations) test.

In order to clarify the distribution of Ni in the solder joint layer initially and after each test, the distribution of Ni was examined by EDS. As a result, after the 200°C storage test, Ni was only present in the Ni-P film 111 layer on the back surface of the heater chip 109 and the copper plate 104 side, and in the alloy layer on the Ni-P film 111 layer. After the TM (thermomigration) test, the Ni-P film 111 layer on the back surface of the heater chip 109 had disappeared, and Ni had diffused to the copper plate 104 side.

From these, it is understood that Ni that was initially present on the rear surface of the heater chip 109 as the Ni--P film 111 layer or (Cu,Ni) ₆ Sn ₅ diffused onto the cold-side Ni--P film 111 layer by the TM (thermomigrations) test.

The diffusion of Cu during a TM (thermomigrations) test was examined. In the initial stage, Cu was present as (Cu, Ni) ₆ Sn ₅ on the rear surface of the heater chip 109. After the TM (thermomigrations) test, Cu was no longer present on the rear surface of the heater chip 109.

Since the (Ni, Cu) ₃ Sn ₄ on the Ni-P film 111 layer on the copper plate 104 side was found to have a thickness of about 10-30 μm in a TM (thermomigra- tion) test, it is considered that the amount of Cu present on the Ni-P film 111 layer on the copper plate 104 side has increased.

Therefore, after the TM (thermomigration) test, Cu is no longer present on the back surface of the heater chip 109, while the amount of Cu present on the Ni-P film 111 layer on the copper plate 104 side increases, so it is inferred that the TM (thermomigration) test caused Cu to diffuse from the back surface of the heater chip 109 (hot side) onto the copper plate 104 (cold side).

In this test, the temperature gradient was 2000-3000°C/cm, and the temperature gradient at the time of occurrence of Cu TM (thermimigration) exceeded 1000°C/cm. Furthermore, considering that the direction of movement was the cold side, the diffusion of Cu to the copper plate 104 side was caused by Cu TM (thermimigration).

After the TM (thermomigration) test, the Ni-P film 111 layer and Ag layer on the back surface of the heater chip 109 disappear, and only Sn can be seen on the back surface of the heater chip 109. This shows that Sn diffuses to the back surface of the heater chip 109 during the TM (thermomigration) test, which is the opposite diffusion direction of Cu and Ni.

Sn is assumed to diffuse to the high temperature side at temperatures above 1000°C/cm. Since the temperature gradient in this test was 2000-3000°C/cm, the diffusion of Sn to the hot side is due to thermomigration (TM) of Sn.

The temperature gradient required for TM (thermomigration) of nickel (Ni) is estimated to be 8050°C/cm. Considering that the temperature gradient in this test was approximately 2000-3000°C/cm, it is unlikely that TM (thermomigration) of Ni is occurring.

At this point in time, it is believed that the alloy layer on the Ni-P film 111 layer is likely to peel off in an environment in which Sn diffuses to the rear surface of the heater chip 109. In that case, it is expected that a new alloy layer containing Ni will form on the Ni-P film 111 layer from which the alloy layer has peeled off. It is believed that this was an environment in which the Ni-P film 111 layer was more likely to be consumed than in the 200°C storage test.

From the above, it was found that when a temperature gradient of about 2000-3000°C/cm is generated in the Sn-0.7Cu/Ni-P film 111 solder joint layer, with the hot side at 200°C, the hot side Ni-P film 111 layer disappears.

Below, we will explain another embodiment of the heater chip of the present invention with reference to the drawings. The explanation will focus on the differences from the previously described embodiment. Therefore, matters that are not specifically mentioned are the same as or similar to the previously described embodiment.

Figure 27 shows a plan view and a cross-sectional view of a heater chip of the present invention in a second embodiment. Figure 27(b) is a cross-sectional view taken along line AA' in Figure 27(a), and Figure 27(c) is a cross-sectional view taken along line BB' in Figure 27(a).

As in the embodiment of FIG. 2, examples of the base substrate 106 include a glass substrate such as SiC (silicon carbide), GaN (gallium nitride), or sapphire glass, an insulating substrate such as AlN ceramics or AlN (aluminum nitride), or a semiconductor substrate.

The base substrate 106 will be described as being made of SiC. However, it goes without saying that any substrate that has good thermal conductivity and insulating or semiconducting properties can be used as the base substrate 106.

The thickness of the base substrate 106 is 0.05 mm or more and 0.8 mm or less. However, the thinner the base substrate 106, the easier it is for heat from the thin-film heater 117 to be transferred to the bonding layer. However, if the base substrate 106 is thin, a temperature distribution is likely to occur in the bonding layer between the areas where the thin-film heater 117 is formed and the areas where it is not formed.

The thin film heater 117 and the temperature probe 116 are made of Ni (nickel)-P or Ni. The thickness of the Ni-P film 111a is preferably 1 μm to 10 μm. It is particularly preferably 2 μm to 6 μm.
The gold plating film 112 has a thickness of 0.01 μm or more and has the function of preventing or suppressing the oxidation or contamination of the surface of the Ni—P film 111.

A thin-film heater 117 and a temperature probe 116 are formed on the surface of the SiC substrate 106. The thin-film heater 117 and the temperature probe 116 are formed of a thin film (Ni-P film 111d) by Ni-P plating. In addition to Ni, they may be made of or formed of platinum (Pt). Other materials that can be used include zinc, tin, lead, and chromium. They can also be made of materials other than metals, such as carbon (C).

The temperature probe 116 is formed from the same material and in the same process as the thin-film heater 117. If the thin-film heater 117 is a Ni-P film, the temperature probe 116 is also formed from a Ni-P film. The temperature probe 116 is formed with a narrow wiring width to increase the resistance of the probe.

A constant current is applied to the temperature probe 116. Increasing the resistance of the temperature probe 116 increases the change in resistance, and increases the voltage change between the terminals of the temperature probe 116 in response to the constant current. This improves the sensitivity of the temperature probe 116 to temperature changes in the thin film heater 117. The resistance of the temperature probe 116 is set to 5 Ω or more and 1 kΩ or less.

Terminal electrodes 114a and 114b are formed on both ends of the temperature probe 116. Terminal electrodes 115a and 115b are formed on both ends of the thin film heater 117.

A gold plating film 112 is formed on the surface of the terminal electrode 114. The gold plating 112 is not only formed on the terminal electrode 114, but also extends to part a of the temperature probe 116.

A gold plating film 112 is formed on the surface of the terminal electrode 115. The gold plating 112 is formed not only on the terminal electrode 115 but also extends to part b of the thin film heater 117.

However, the gold plating film 112 is not formed on the thin film heater 117 and the temperature probe 116. If the gold plating film 112 is formed, the resistance value of the thin film heater 117 and the temperature probe 116 will decrease, and the sensitivity to heat generation or temperature changes will decrease. The sheet resistance value of the thin film heater 117 and the temperature probe 116 is made higher than the sheet resistance value of the electrode terminal.

A single layer or multilayer film made of a _SiO2 film, a _SiNx film, or a SiON film may be formed on the thin film heater 117 and the temperature probe 116. By forming an inorganic thin film such as a _SiO2 film, the surfaces of the thin film heater 117 and the temperature probe 116 can be prevented from being oxidized or contaminated.

Although the description will be given assuming that a thin-film heater 117 is formed on the SiC substrate 106, this is not limited to this. The thin-film heater 117 is arranged or formed in order to heat the substrate 106. As an alternative to the thin-film heater 117, a surface heater incorporating Nichrome wire, a heater using a Peltier element, or the like may be used. The base substrate 106 can be heated by passing a current through a surface heater incorporating Nichrome wire or a Peltier element.

A polyimide (PI) tape (sheet) 107 or the like is attached to the polished end face C. A predetermined constant current is applied to the thin film heater 117 serving as the heater chip 109, and the heat generated by the constant current heats the solder or other bonding layer while the polished portion of the end face is observed or measured with an infrared thermography camera or the like. The observation or measurement is performed through the polyimide film. The temperature of the bonding layer of the polished portion is measured at multiple points to determine temperature information ΔT between the multiple points.

In addition, a photosensitive polyimide film 107 is formed on the polished end surface C. The photosensitive polyimide film 107 is formed or placed on the polished surface by a spin coating method, a slit coating method, a screen printing method, an inkjet spraying method, a spray coating method, a die coating method, a doctor knife coating method, flexographic printing, or the like.

The photosensitive polyimide film 107 and the polyimide (PI) tape (sheet) 107 basically have the same or similar functions. In the following, the polyimide tape 107 will be mainly used as an example for explanation. It goes without saying that the polyimide tape 107 may be replaced with the polyimide film 107.

In the heater chip 109 of the present invention, an example is shown in which a polyimide tape 107 is attached to the end face and the temperature of the surface of the polyimide tape 107 is measured using an infrared thermography camera 108.

Thermal conduction causes a temperature drop within the polyimide tape 107, so the temperature measured by the infrared thermography camera 108 is lower than the actual temperature of the end surface.

The graph in Figure 23 shows the temperature (°C) of the temperature probe 116 and the thermography temperature (°C) measured by the infrared thermography camera 108 when electricity is applied to the thin film heater 117 with the polyimide tape 107 attached to the polished surface.

In FIG. 23, the black dots indicate the temperature of the temperature probe 116. The temperature of the temperature probe 116 is the value obtained by measuring the voltage between the terminals of the temperature probe 116 when a constant current is applied and converting it into temperature. The scale axis is shown on the left. The white dots indicate the temperature drop in the polyimide tape 107, and the scale axis is shown on the right.

The temperature drop in the polyimide tape 107 is a value calculated by the following formula using the temperature probe 116 and the thermography temperature (°C) measured by the infrared thermography camera 108. The measurement point by the infrared thermography camera 108 is the dotted line position F in Figure 25.
Temperature drop in polyimide tape 107 (°C)=Temperature probe (°C)-Thermography temperature (°C).

For example, if the thermography temperature (°C) measured by the infrared thermography camera 108 is 200°C, the temperature drop (°C) in the polyimide tape 107 is 35°C. Therefore, to make the end face 200°C, the thermography temperature should be set to 200°C-35°C=165°C.
Needless to say, when carrying out the experiment at other end surface temperatures, the appropriate thermography temperature can be read from the graph in FIG.

If the infrared thermography camera (infrared camera) 108 is a cooled type equipped with a Stirling cooler, the Stirling cooler will need to be replaced, which is expensive, considering that the average time to failure of a Stirling cooler is 10,000 hours and that this test will last for several hundred hours. Therefore, it is not economical to use the infrared thermography camera 108 to control the temperature during the test.

Figure 24 is an explanatory diagram of the evaluation method of the bonding layer, etc. of the present invention. The temperature of the bonding layer is measured by an infrared camera 108. The temperature measured by the infrared camera 108 increases with the test time. The temperature increases with the application of a set current. Usually, the temperature measured by the infrared camera 108 reaches a steady value within 2 minutes, as shown by the solid line in Figure 24.

Meanwhile, the temperature is monitored by the temperature probe 116. The temperature monitored by the temperature probe 116 increases with the test time. The temperature increases due to the application of a predetermined constant current to the temperature probe 116, and the monitored temperature usually reaches a steady value within two minutes, as shown by the dotted line in FIG.
As described with reference to FIG. 23, a difference occurs between the temperature monitored by the temperature probe 116 and the temperature measured by the infrared camera 108.

The temperature probe 116 is formed or placed on the heater chip 109. Before the test, the temperature is measured with the infrared camera 108, and when the temperature reaches a steady value at time t, the temperature is switched to temperature monitoring with the temperature probe 116 (control target switching).

As described above, by using the heater chip 109 equipped with the temperature probe 116, it is not necessary to occupy an expensive infrared camera 108. In other words, measurements or evaluation tests using a plurality of heater chips 109 can be performed with a single infrared camera 108.
Before the start of the test, the temperature is controlled by the infrared camera 108 and adjusted to the target test temperature. At this time, the temperature is also monitored by the temperature probe 116.

At time t when the target test temperature is reached, a command is issued to the programmable DC power supply 803 to control the temperature of the temperature probe 116 to a constant temperature. At this point, the test is started. In other words, control is switched to that by the temperature probe 116.
It goes without saying that the temperature control may be switched back to the infrared camera 108 after a certain period of time has elapsed based on an arbitrary standard, or when there is a continuous change in the output of the DC power supply, or the like.

As shown in FIG. 25, high-temperature solder 126 is formed or placed on terminal electrode 114 and terminal electrode 115, and wiring 127 is attached to high-temperature solder 126. A current power supply device 803 is placed on each wiring 127, and a constant current output by current power supply device 803 is applied to terminal electrode 114 or terminal electrode 115.

For high-temperature solder, it is preferable to use solder with a lead content of 90% or more, and more preferably 95% or more. With a higher lead content, the melting point increases to 300°C, and its softness makes it more resistant to thermal fatigue.

High-temperature solder 126d is formed or placed on terminal electrode 115a, and wiring 127d is attached to high-temperature solder 126d. High-temperature solder 126e is formed or placed on terminal electrode 115b, and wiring 127e is attached to high-temperature solder 126e.

High temperature solder 126f is formed or placed on terminal electrode 114a, and wiring 127f is attached to high temperature solder 126f. High temperature solder 126g is formed or placed on terminal electrode 114b, and wiring 127g is attached to high temperature solder 126g.
25, the section between a and a is the temperature probe 116. The resistance between a and a is preferably 5 Ω or more and 1000 Ω or less, and more preferably 10 Ω or more and 500 Ω or less.
The area between bb and ' constitutes the thin film heater 117. The resistance between bb and ' is preferably 5 Ω or more and 500 Ω or less, and more preferably 10 Ω or more and 200 Ω or less.

The Ni--P layer 111 has poor thermal stability of wiring resistance after plating. The thin film heater 117 and the temperature probe 116 are at temperatures between 100° C. and 300° C. during testing, and the wiring resistance of the temperature probe 116 and the like decreases during testing.
This makes it difficult to measure temperature using a temperature probe (converting voltage to temperature) and to control the temperature using a control app.

In the present invention, the heater chip 109 after plating with the Ni--P layer 111 is heat-treated at a temperature of 250° C. to 350° C. for 6 hours or more, and more preferably for 10 hours or more.
The heat treatment stabilizes the wiring resistance of the thin film heater 117 and the temperature probe 116. Fig. 26 is a graph showing the change in resistance due to the heat treatment.

The state where soldering is performed within the shaded area in Figure 25 is described as "after soldering." Soldering is performed before heat treatment. This is because if heat treatment is performed without soldering, the solder will not wet or the wettability will deteriorate at terminal electrodes 114 and 115.

By soldering within the shaded area in FIG. 25, the resistance values of the temperature probe 116 and the thin-film heater 117 decrease. For example, the wiring resistance of the temperature probe 116 decreases from 130 Ω to approximately 50 Ω by soldering. The wiring resistance of the thin-film heater 117 decreases from approximately 50 Ω to approximately 25 Ω by soldering.

After soldering, heat treatment is performed, which reduces the resistance of the thin-film heater 117 and temperature probe 116. After 6 hours of heat treatment, the resistance of the wiring (thin-film heater 117 and temperature probe 116) is almost stable, and after 10 hours of heat treatment, the resistance of the wiring (thin-film heater 117 and temperature probe 116) is completely stable. Furthermore, if heat treatment is performed without soldering, the solder will not wet the terminal electrodes.

The heat treatment time was determined based on a prior investigation into the change in wiring resistance versus heat treatment time at 300°C. This is a necessary process for the heater chip to be produced using Ni-P plating.

A lead wire 121 is soldered to the terminal electrodes 114 and 115 or a probe (not shown) is pressure-welded thereto, and a constant current outputted from a current power supply 803 is applied to the terminal electrodes 114, 115, 124, and so on.
Hereinafter, a method for producing the heater chip 109 of the present invention shown in FIG. 27, FIG. 28, etc. will be described with reference to the drawings.
29 to 33, the left side of each figure shows a side view of the heater chip, and the left side of each figure shows a plan view of the heater chip 109.

As shown in Fig. 29(a1) and Fig. 29(a2), a mask 501a is applied to the front surface of the SiC substrate 106. Similarly, a mask 501b is applied to the rear surface of the SiC substrate 106. The mask 501 preferably contains an alkali-soluble acrylic polymer.

Next, the surface of the SiC substrate 106 is roughened using a femtosecond laser device (not shown) (FIG. 29(b1), FIG. 29(b2)). Femtosecond laser light 502 or picosecond laser light 502 is irradiated to roughen the portions of the surface of the SiC substrate 106 that correspond to the temperature probe 116, the thin film heater 117, the terminal electrode 114, and the terminal electrode 115.

By irradiating the SiC substrate 106 with picosecond laser light 502 or femtosecond laser light 502, a roughened surface 119a is formed on the temperature probe 116, thin film heater 117, terminal electrode 114, terminal electrode 115, and thin film heater 117.

In particular, since a femtosecond green laser is a second harmonic, it is possible to extract a relatively high output, and the irradiated laser light is well absorbed by the SiC substrate 106 .
The roughened arithmetic mean roughness Ra is 0.2 μm or more, and more preferably 0.3 μm or more, 0.4 μm or more, and 0.5 μm or more, in that order.
By irradiating a pulse of femtosecond laser light 502, the portions of the mask 501 corresponding to the portions where the thin film heaters 117 and the like are to be formed are removed, and recesses are formed.

Patterning of wiring (thin film heater 117, temperature probe 116, etc.) may be performed based on marks 130 formed on the surface of mask 501. Positioning is performed based on cross marks 130, etc. formed on SiC substrate 106. The cross marks 130 are image-recognized by a camera to position SiC substrate 106. At least two cross marks 130, etc. are provided on diagonal lines, etc.

The cross mark 130 formed on the SiC substrate 106 is captured by a camera, the cross mark 130 is image-recognized, the position of the cross mark 130 is compared with the design coordinates, and the patterning (thin film heater 117, temperature probe 116, etc.) position (the location where the laser light is irradiated) is positioned, and the laser light 502 is irradiated.
The roughening state can be easily varied by changing or setting the laser intensity of the femtosecond laser light 502 and the moving speed of the irradiated laser pulse.

The SiC substrate 106 is degreased using an acidic degreaser at 45°C for 5 minutes, for example. A pre-dip process is performed using a hydrochloric acid aqueous solution. The retention time is, for example, 2 minutes.

Next, as shown in FIG. 30(c1) and FIG. 30(c2), a Sn--Pd catalyst 504a is applied, coated or formed on the roughened surface 119 and the surface of the remaining portion of the mask 501a.
The Sn--Pd catalyst 504a is a colloidal particle, and a Sn-rich layer and a Sn2+ layer are formed in this order on the surface of the Sn--Pd core.

By immersing the SiC substrate 106 with the Sn-Pd catalyst 504a in a hydrochloric acid solution, the Sn layer is removed and the internal Pd catalyst is exposed. Since the Pd catalyst is exposed, a reaction occurs in the electroless Ni-P plating solution (described later) in the area where the Sn-Pd catalyst 504a is present.

Next, as shown in Fig. 30(d1) and Fig. 30(d2), the mask 501a is peeled off using an alkaline solution. As shown in Fig. 30(d1), the Sn-Pd catalyst 504a is no longer present in the portion of the SiC substrate 106 where the mask 501 has been peeled off.

Next, as shown in Figures 31(e1) and 31(e2), electroless Ni-P plating is performed on the surface of the SiC substrate 106 to form the temperature probe 116 and the thin-film heater 117.

Next, as shown in FIG. 31(f1) and FIG. 30(f2), masking tape 120a is formed or placed around the areas where the temperature probe 116 and thin film heater 117 will be formed.

Masking tape 120a is not formed or placed on the portions where terminal electrodes 114 and 115 are formed. In addition, masking tape 120a is not formed or placed on portions a and b near the electrodes shown in FIG. 31(f2).

In FIG. 31(f2), consider the case where masking tape 120c is formed or positioned so as to coincide with the ends of terminal electrode 114 and terminal electrode 115, as shown by the dotted lines in FIG. 27(a).

In the case of the dotted line in Figure 27 (a), the displacement Au plating solution penetrates into the end of the masking tape 120c, and Au plating is formed on the Ni-P of the straight line section. If solder flows into this area during soldering, the Ni-P layer is thin, making it prone to breakage due to solder erosion. If a break occurs, the heater chip 109 will break and the test will be stopped. In other words, the life of the heater chip 109 will be shortened.

To avoid this phenomenon, as shown in FIG. 31(f2), masking tape 120a is formed or positioned so as not to cover parts a and b. In other words, a Ni-P layer of the same thickness as the pad part is formed only in a portion of the straight parts of thin film heater 117 and temperature probe 116, so that even if solder flows into the straight parts, it will not break.

As shown in Figures 32(g1) and 32(g2), masking tape 120a is formed or placed around the areas where the thin film heater 117 and temperature probe 116 will be formed.

Masking tape 120a is not formed or placed on the portion where terminal electrode 115 is formed, or on portions b and b'. Also, masking tape 120a is not formed or placed on the portion where terminal electrode 114 is formed, or on portions a and a'.

As shown in Figures 32(h1) and 32(h2), similar to Figures 20(k1) and 20(k2), electroless Ni-P plating is performed on the surface of the SiC substrate 106, and an electroless Ni-P plating film 111b is formed on the terminal electrodes 115, 114, etc.

As shown in FIG. 32(g1), the thin film heater 117 and temperature probe 116 are formed with electroless Ni-P plating film 111a. The terminal electrode 115 and terminal electrode 114 are formed by laminating electroless Ni-P plating film 111a and electroless Ni-P plating film 111b.

Therefore, the terminal electrodes 115 and 11 have a lower resistance than the thin-film heater 117. Because the terminal electrodes 115 and 114 have a small resistance, they do not generate heat even when a specified constant current is applied to them. Because the thin-film heater 117 has a high resistance, it generates heat well when a specified constant current is applied to it.

As shown in Figures 32(h1) and 32(h2), a substituted Au film (terminal electrode 114) is formed on terminal electrode 114, a, and a'. A substituted Au film (terminal electrode 115) is formed on terminal electrode 115, b, and b'. As described above, a gold plating film 115 is formed on the surface of Ni-P film 111b in the areas corresponding to the terminal electrodes.

Next, as shown in Figure 33 (i1) and Figure 33 (i2), the masking tapes 120a and 120b are peeled off. By peeling off the masking tape 120a, the Ni-P plating film 111a as the thin film heater 117 is exposed. In addition, the Ni-P plating film 111a as the temperature probe 116 is exposed.
Through the above steps, the terminal electrodes 115 and the thin film heaters 117 are formed on the SiC substrate 106 .

Next, as shown in Figures 33(j1) and 33(j2), the end faces of the heater chip 109 are polished from the c-face. By polishing the end faces, the end faces of the thin film heater 117 are exposed on the side faces. In addition, CP processing is performed on the bonding layer 105 as necessary.

When evaluating the bonding layer, a polyimide film 107 is attached to the polished surface. Alternatively, a photosensitive polyimide film is formed on the surface of the bonding layer 105. The photosensitive polyimide film is formed on the polished surface. The portion where the photosensitive polyimide film is formed includes at least the bonding layer to be evaluated.
The infrared thermography camera 108 measures the two-dimensional temperature distribution of the bonding layer, etc. through the polyimide film 107 .

Hereinafter, a heater chip according to another embodiment of the present invention will be described. FIG. 34 is a plan view of a heater chip 109 according to another embodiment of the present invention, and FIG. 35 is a side view of a heater chip 109 according to another embodiment of the present invention.

With reference to Figure 34 etc., we will explain the combined test heater chip 109 that can simultaneously perform both thermomigration (TM) testing and electromigration (EM) testing.

When conducting a combined test (TMEM test) that simultaneously investigates the effects of thermomigration (TM) and electromigration (EM) tests, it is necessary to generate a temperature gradient at the solder joint and apply a current to the solder joint.

By conducting continuous current tests on power modules and TO-247 packages, the elements heat up and current flows through the solder joints, allowing the effects of thermomigration (TM) and electromigration (EM) to be observed.

The junction temperature is determined depending on the resistance (on-resistance, etc.) of the semiconductor element. For example, it is difficult to achieve a high current density when the junction temperature is relatively low. Conversely, it is also difficult to achieve a constant current density when the junction temperature is high. Therefore, in conventional continuous current tests, there were limitations on the test temperatures and current densities that could be selected.

In the present invention, as shown in FIG. 34, a current application path 132 is formed or arranged on the heater chip 109. Terminal electrodes 124a and 124b are arranged on both ends of the current application path 132.

The current application path 132, terminal electrode 124a, and terminal electrode 124b are formed of Ni-P111, similar to the temperature probe 116, and have gold plating 112 on their surfaces.

34 , high temperature solder 126 is formed or placed on terminal electrodes 114, 115, and 124, and wiring 127 is attached to high temperature solder 126. A current power supply device 803 is placed on each wiring 127, and a constant current output by current power supply device 803 is applied to terminal electrode 114, terminal electrode 115, or terminal electrode 124.
A high-temperature solder 126d is formed or placed on the terminal electrode 115a, and a wiring 127d is attached to the high-temperature solder 126d.
High temperature solder 126e is formed or placed on terminal electrode 115b, and wiring 127e is attached to high temperature solder 126e.
High temperature solder 126b is formed or placed on terminal electrode 124a, and wiring 127b is attached to high temperature solder 126b.
A high temperature solder 126c is formed or placed on the terminal electrode 124b, and a wiring 127c is attached to the high temperature solder 126c.
High temperature solder 126f is formed or placed on terminal electrode 114a, and wiring 127f is attached to high temperature solder 126f.
High temperature solder 126g is formed or placed on terminal electrode 114b, and wiring 127g is attached to high temperature solder 126g.

A temperature probe 116 is placed between terminal electrode 114a and terminal electrode 114b, and a constant current is applied to the temperature probe 116. The voltage between terminal electrode 114a and terminal electrode 114b can be measured. The constant current can be variably set.

A thin-film heater 117 is disposed between the terminal electrodes 115a and 115b, and a constant current is applied to the thin-film heater 117. The constant current is configured to be variably set.

A current application path 132 is formed or disposed between the terminal electrodes 124a and 124b. A constant current is applied to the current application path 132. The constant current is configured to be variably set. The surfaces of the terminal electrodes 124a, 124b, and current application path 132 are gold plated 112, which is formed to reduce resistance.
High temperature solder 126a is also connected or placed on metal plate (copper plate) 129, and wiring 127a is connected to high temperature solder 126a.

For ease of explanation, the metal plate (copper plate) 129 will be described, but it is not limited to a metal plate and any substrate or sheet having good thermal conductivity may be used. For example, a sheet or substrate made of carbon graphite is exemplified. In this case, pressure bonding or fusion bonding is performed.
34, the section between a and a' corresponds to the temperature probe 116. The resistance between a and a' is preferably 5 Ω or more and 1000 Ω or less, and more preferably 10 Ω or more and 500 Ω or less.
The area between bb and ' constitutes the thin film heater 117. The resistance between bb and ' is preferably 5 Ω or more and 500 Ω or less, and more preferably 10 Ω or more and 200 Ω or less.
The resistance value of the current application path 132 is desirably small, and is formed to be at least smaller than the resistance value of the thin film heater 117 .

35, a thin film heater 117, a temperature probe 116, and a current application path 132 are formed on a SiC substrate 106. The SiC substrate 106 is connected to a copper plate 104 by a sintered Ag paste filling layer 125. The copper plate 104 is preferably an oxygen-free copper plate, but needless to say, other metals may be used.
The sintered Ag paste is also filled into through holes (TH) 131 formed in the SiC substrate 106 to form sintered Ag paste filled portions 134 .

The metal plate (copper plate) 129 has a heat dissipation function. The material of the metal plate (copper plate) 129 is not limited to copper, and it goes without saying that other metals may be used. The metal plate (copper plate) 129 and the copper plate (oxygen-free copper plate) 104 are connected by a solder layer serving as a bonding layer 105.
As shown in FIGS. 35 and 36, a constant current 128a for electromigration (EM) is supplied from an EM DC power supply device 803c.

The constant current 128a becomes constant current 128b, and flows through the sintered Ag paste filling layer 125, the sintered Ag paste filling portion 134 charged in the through hole (TH) 131, and the like, into the current application path 132.

As shown in FIG. 36, constant current 128b becomes constant current 128c and constant current 128e. Constant current 128c flows into terminal electrode 124a. Constant current 128e flows into terminal electrode 124e.

By changing or setting the magnitude and flow direction of the constant current 128a to a predetermined value, the electromigration (EM) test can be performed satisfactorily. In addition, the effect of electromigration (EM) can be effectively exerted.

It is preferable that the constant current 128a is linked to the constant current 128d for thermomigration (TM). It is also linked to the temperature or current of the thin film heater 117 and the temperature probe 116.

The constant current 128d for thermomigration (TM) is supplied from the EM DC power supply device 803d. The constant current 128d flows through the thin film heater 117a and the thin film heater 117b.

It is preferable that the constant current 128d is linked to the constant current 128a for electromigration (EM). The constant current 128d for thermomigration (TM) is linked to the temperature or current of the thin film heater 117 and the temperature probe 116.

As described above, the heater chip 109 shown in Figures 34, 35, 36, etc. can perform thermomigration (TM) and electromigration (EM) with freely selectable test temperatures and current densities by forming or arranging a current application path 132 in addition to the heater chip 109 in Figure 27. A heater chip for composite testing that can perform thermomigration (TM) and electromigration (EM) has been realized.

Fig. 37 is a graph showing the relationship between current density (kA/ ^cm2 ) and junction temperature (°C) in the heater chip of the present invention. In the graph of Fig. 37, when the current density (kA/ ^cm2 ) is 0, the junction temperature (°C) is 50°C. As the current density (kA/ ^cm2 ) increases, the junction temperature (°C) rises, and when the current density (kA/ ^cm2 ) is 4 (kA/ ^cm2 ), the junction temperature (°C) is 95°C.

If the application of an electromigration (EM) current causes the junction to reach approximately 200°C, a thermomigration (TM) test cannot be performed at the same time. In Figure 37, the junction temperature caused by the application of an electromigration (EM) current is several tens of degrees Celsius. Therefore, it is entirely possible to perform a thermomigration (TM) test at the same time.

From the results of FIG. 37 etc., the heater chip 109 of the present invention described in FIG. 35 and FIG. 36 can be subjected to a combined test of a thermomigration (TM) test and an electromigration (EM) test.
In the present invention, a composite test is carried out by placing or disposing an evaluation sample on a heat sink 129 maintained at 50°C.

According to the results of the investigation of the range of current density (kA/ ^cm2 ) conditions, it is said that electromigration (EM) of tin (Sn) occurs. Therefore, by using the heater chip of the present invention, it is possible to secure a current density of kA/ ^cm2 , and it is possible to carry out a thermomigration (TM) test and/or an electromigration (EM) test.
Hereinafter, a method for manufacturing (fabricating) the heater chip 109 of the present invention shown in FIGS. 34, 35, 36, etc. will be described with reference to the drawings.

Figures 38 to 40 are explanatory diagrams of a method for producing the heater chip 109 of the present invention. In the following explanation, as in other embodiments, similar or equivalent matters and contents may be omitted. It goes without saying that the following embodiments can be combined with or substituted for other embodiments.

As in the other embodiments, a mask is applied to the surface of the SiC substrate 106 shown in FIG. 38(a). The mask preferably contains an alkali-soluble acrylic polymer.

As shown in FIG. 38(b), the surface of the SiC substrate 106 is roughened using a femtosecond laser device (not shown). Femtosecond laser light or picosecond laser light 502 is irradiated to roughen the portions of the surface of the SiC substrate 106 that correspond to the temperature probe 116, the thin film heater 117, the terminal electrode 114, the current application path 132, the terminal electrode 115, and the terminal electrode 124.

By irradiation with femtosecond laser light 502 or the like, roughened surfaces 119 a are formed on temperature probe 116 , thin film heater 117 , terminal electrode 114 , terminal electrode 115 , terminal electrode 124 , and current application path 132 of SiC substrate 106 .
By irradiating a pulse of femtosecond laser light 502, the portions of the mask corresponding to the portions where the thin film heaters 117 and the like are to be formed are removed, and recesses are formed.
The patterning of the wiring (thin film heater 117, temperature probe 116, etc.) may be performed based on marks 130 formed on the surface of the mask.

The SiC substrate 106 is degreased using an acidic degreaser at 45°C for 5 minutes, for example. A pre-dip process is performed using a hydrochloric acid aqueous solution. The retention time is, for example, 2 minutes.

Next, as described in Figures 31 to 33, etc., a Ni-P film (plating film) and a gold plating film 112 are formed, and a temperature probe 116, a thin film heater 117, a current application circuit 132, terminal electrodes 124, 114, and 115 are formed (Figure 38 (c)).

By forming a gold plating film 112 over the entire current application path 132, the resistance between the terminal electrodes 124a and 124b is reduced, making it easier for the applied EM current 128a to flow.

In FIG. 38(c), a through hole (TH) 131 is formed. The through hole (TH) 131 is formed by electric discharge machining, laser machining, or sandblasting.

Electrical discharge machining (EDM) is a machining method that removes part of the surface of a workpiece by repeatedly discharging an arc between an electrode and the workpiece in short cycles. It is applied when the substrate 106 is conductive.

Sandblasting involves mixing abrasives with compressed air produced by a compressor and spraying the mixture, but when processing small parts, the process is carried out in a work box called a sandblaster in order to spray a larger amount of abrasives more efficiently.

For laser processing, it is preferable to use a femtosecond green laser. The femtosecond green laser can use the laser device that roughened the surface 119 in the present invention. Therefore, no new device is required, which is preferable.

Through holes (TH) 131 are created by processing such as sandblasting. The through holes (TH) are holes that penetrate the substrate 106 such as SiC. Note that in Figures 38(b) and 38(c), the through holes (TH) 131 are illustrated as rectangular, but are not limited to this. For example, they may be polygonal, such as circular, elliptical, or hexagonal. As will be described later, the through holes (TH) 131 may be of any shape as long as they can be filled well with the sintered Ag paste.

Next, as shown in FIG. 39(d), high-temperature solder 126 is formed or placed on terminal electrodes 114, 115, and 124, and wiring 127 is attached to high-temperature solder 126.

A direct current power supply device 803d for thermomigration (TM) is connected to the wiring 127e and the wiring 127d. A direct current power supply device 803c for electromigration (EM) is connected to the wiring 127b and the wiring 127c.
A solder layer (bonding layer) 105 is formed between the copper plate 104 and a metal plate (copper plate or a substrate having good conductivity) 129 that has a heat dissipation function or maintains a predetermined temperature.

Sintered Ag paste is applied onto the copper plate 104. The sintered Ag paste is placed or formed on the copper plate 104 by screen printing or spinner application.

As shown in FIG. 39(d), the heat chip 109 is placed on the sintered Ag paste, and the copper plate 104 and the heat chip 109 are connected. At this time, the sintered Ag paste is filled into the through-hole 131 of the SiC substrate 106, forming the sintered Ag paste filled portion 134.

The sintered Ag paste is heated from room temperature (RT) to 200°C over a period of 30 to 60 minutes. It is sintered by holding it at 200°C for 30 to 90 minutes. Sintering allows the substrates to adhere closely to each other. Sintering also results in a low resistance of 3.0 μΩ cm or less.

Filling the through-holes (TH) 131 with sintered Ag paste provides good electrical connection between the thin-film heaters 117a and 117b, and also provides good electrical connection between the current application path 132 and the thin-film heater 117 (Figure 39 (e)).

39(e), the end face of the heater chip 109 is polished from the end face to the line dd'. By polishing the end face, the end face of the thin film heater 117 is exposed on the side face. If necessary, the end face is processed with a cross section polisher (CP).
By polishing the end surface, the sintered Ag paste filled portion 134 in the through hole (TH) 131 exposed at the end surface is exposed as shown in FIG. 40( f ).
Next, as shown in FIG. 40(f), high temperature solder 126a is soldered to the copper plate 129, and wiring 127a is connected to the high temperature solder 126a.

40G, when evaluating the bonding layer, etc., a polyimide film 107 is attached to the polished surface. Alternatively, a photosensitive polyimide film is formed on the bonding layer 105 surface.
The infrared thermography camera 108 measures the two-dimensional temperature distribution of the bonding layer 105 through the polyimide film 107 .
As described above, the bonding layer evaluation method and bonding layer evaluation device of the present invention can quantitatively evaluate the evaluation, configuration, life, etc. of the bonding layer.

The embodiments illustrated in Figures 1, 2, 22, 27, 34, 39, etc. have a configuration having one heater chip 109. Electricity is passed through the thin film heater 117 of the heater chip 109 to heat the bonding layer 105, etc.

By heating or the like, thermomigration (TM) and electromigration (EM) occur in the bonding layer 105 or the like, and the occurrence, changes, and structure of the thermomigration (TM) and electromigration (EM) are measured, evaluated, or inspected.

In one embodiment of the present invention, a temperature gradient is created in the solder bonding layer 105, with the back surface of the heater chip 109 being the hot side (heating side) and the copper plate 104 being the cold side (cooling side).

In order to visualize the temperature gradient that occurs, the temperature gradient is determined from the temperature difference between the Ni-P film 111 layer on the back surface of the heater chip 109 (hot side Ni-P film 111 layer) and the Ni-P film 111 layer on the copper plate 104 side (cold side Ni-P film 111 layer).

Figure 41 is an explanatory diagram showing the relationship between the hot side temperature (°C) and the temperature gradient (°C/cm). One graph (upper side) is an example of a sample (measurement object) with a large temperature gradient, and the other graph (lower side) is an example of a sample (measurement object) with a small temperature gradient.

Some samples (objects to be measured) have a large temperature gradient (°C/cm) relative to the hot side temperature (°C), while others have a small temperature gradient (°C/cm) relative to the hot side temperature (°C). Even among the samples to be produced, there is a large variation in the temperature gradient (°C/cm) relative to the hot side temperature (°C). This occurs due to the state of the bonding layer 105, the bonding state between the copper plate 104 and the bonding layer 105, etc.

In Figure 41, in the sample with a small temperature gradient, TM occurs when the hot side temperature is around 175°C. In the sample with a large temperature gradient, TM occurs when the hot side temperature is around 150°C. Therefore, the temperature at which TM occurs varies depending on the temperature gradient.

When changing the temperature gradient by changing the sample structure, it is often difficult to change it continuously, and even with the same sample structure, differences of several hundred degrees Celsius/cm occur.
In order to perform good EM and TM observations, it is necessary to be able to arbitrarily control the temperature gradient.

It is preferable that the evaluation of EM and TM in the bonding layer 105 can be performed without being affected by the temperature gradient of the sample (measurement object). In addition, it is preferable that the occurrence of EM and TM can be observed at a constant temperature for each sample (measurement object) without being affected by the hot side temperature (° C.).
FIG. 42 is an explanatory diagram of the heater chip of the present invention, a configuration having the heater chip and a bonding layer, and an explanatory diagram of an evaluation method, a measurement method, and an inspection method of the bonding layer.
In FIG. 42, the bonding layer is illustrated as a bonding layer 304 having a tin (Sn) layer 301 and a solder resist (SR) layer 302, and will be described.

In FIG. 42 etc., it goes without saying that the heater chip 109 can be the one described in this specification in FIG. 2, FIG. 7, FIG. 16, FIG. 17, FIG. 27, FIG. 28, FIG. 34, FIG. 38, etc.

In this specification, the heater chip 109 is described, but it goes without saying that the shape is not limited to a chip, and the technical concept of the present invention can be applied to other shapes such as a substrate shape, a film shape, a three-dimensional shape, a flat shape, a plate shape, an arc shape, etc.

The heater chip 109 has at least a thin-film heater 117 formed on the SiC substrate 106 or the like as a heat generating means. The thin-film heater 117 has a terminal electrode 115 formed thereon, and a wiring 127 (not shown) is connected to the terminal electrode 115 by high-temperature solder 126. A current is supplied to the thin-film heater 117 by a current power supply device 803 (not shown), and the thin-film heater 117 generates heat to heat the joint 304 or the like.

As shown in FIG. 42, the heater chip 109a is bonded to the copper plate 104a (hot side copper plate) by a sintered Ag layer 125a (sintered Ag paste, etc.). The heater chip 109b is bonded to the copper plate 104b (cold side copper plate) by a sintered Ag layer 125b (sintered Ag paste, etc.).

A Ni-P film (plating film) 111 is formed on the copper plate 104. The bonding layer 304 is bonded to the copper plate 104a via the Ni-P film (plating film) 111a. The bonding layer 304 is bonded to the copper plate 104b via the Ni-P film (plating film) 111b.

Heater chips 109 are attached to the upper and lower sides of the bonding layer 304, and current can be applied independently to the thin-film heaters 117 of each heater chip 109. In addition, the current applied to the thin-film heaters 117a and 117b is configured to be independently adjustable and variable.

In FIG. 42, there are two heater chips 109, one on the top surface and one on the bottom surface of the bonding layer 304, but this is not limited to this. It goes without saying that three or more heater chips 109 may be used or placed. For example, a configuration in which heater chips 109 are used or placed on the side surface of the copper plate 104 in addition to the top and bottom surfaces is exemplified.

Figure 43 is an explanatory diagram of a configuration in which the bonding layer evaluation configuration of the present invention using multiple heater chips 109 described in Figure 42 is placed or attached to a heat sink 129 (heat sink).

The copper plate 104b is attached to the heat sink 129 by bolts 305. Note that the attachment is not limited to bolts 305, and the copper plate 104b may be connected by pressure welding, or may be attached by applying pressure with a clip or the like. It is preferable to apply heat dissipation (heat transfer) grease (not shown) between the copper plate 104b and the heat sink 129.

The bonding layer 304 is arranged in such a manner that it is sandwiched between a Ni-P film (plating film) 111a formed on the hot side copper plate 104a and a Ni-P film (plating film) 111b formed on the cold side copper plate 104b.

The heater chip 109a is attached to the hot side copper plate 104a via sintered Ag paste 125a. The heater chip 109b is attached to the cold side copper plate 104b via sintered Ag paste 125b.

A current is applied to the thin-film heater 117a of the heater chip 109a by a current power supply device 803a. By varying the magnitude of the current, the thin-film heater 117a generates heat and the amount of heat generated can be varied. A current is applied to the thin-film heater 117b of the heater chip 109b by a current power supply device 803b. By varying the magnitude of the current, the thin-film heater 117b generates heat and the amount of heat generated can be varied.

Although not shown in FIG. 43 etc., a voltage application means is arranged to apply an electric field to the junction layer 304 and move electrons, and the applied voltage can be varied.

As described above, the currents applied to the thin-film heaters 117a and 117b can be changed independently by the current power supply devices 803a and 803b. Therefore, the heating temperature Ta by the thin-film heater 117a and the heating temperature Tb by the thin-film heater 117b can be freely set.

The temperature probe 116 is not shown in Figures 42, 43, etc., but the temperature of the heater chip 109 is obtained by the temperature probe 116 as described in Figures 1, 2, 7, 17, 25, 34, 36, etc.

Figure 44 is an explanatory diagram of the method for evaluating the bonding layer of the present invention using the configuration described in Figures 42 and 43. In Figure 44, an electric field or voltage is applied to the bonding layer 304 so that the movement of electrons e occurs.

In Fig. 44(a), the temperature of the heater chip 109a is Ta0°C, and the temperature of the heater chip 109b is Tb0°C. In Fig. 44(b), the temperature of the heater chip 109a is Ta1°C, and the temperature of the heater chip 109b is Tb1°C. In Fig. 44(c), the temperature of the heater chip 109a is Ta2°C, and the temperature of the heater chip 109b is Tb2°C. Fig. 44(a) is assumed to be the initial stage, and Fig. 44(c) is assumed to be the final stage.
The temperature of the heater chip 109a is set to Ta0>Ta1>Ta2, and the temperature of the heater chip 109b is set to Tb0>Tb1>Tb2.
As described with reference to FIGS. 1, 6, 15 and 40, the temperature of the tin (Sn) layer 301 of the bonding layer 304 is measured or evaluated using the infrared camera 108 as a change in temperature.

In the case of EM testing or EM evaluation, in the early stage of FIG. 44(a), the tin (Sn) layer 301 rises by several degrees Celsius. In FIG. 44(b), the tin (Sn) layer 301 rises by several tens of degrees Celsius. In the final stage of FIG. 44(c), the tin (Sn) layer 301 rises by 100 to 200 degrees Celsius.

The test was stopped when the temperature rise due to Joule heating of the solder layer exceeded the test temperature. For example, under the condition of 30 kA/ ^cm2 , the heat generated by the solder layer exceeded 200°C at the 73-hour mark, so the test was stopped.

44, the temperature Ta and the temperature Tb can be varied or set independently. Therefore, EM testing can be performed without melting even at a high current density of about 30 kA/ ^cm2 .

Figures 45 and 46 are explanatory diagrams of the temperature gradient control method in Figure 44. Figure 45 is an explanatory diagram comparing the temperature distribution data in Figure 46 (a) with the configuration of the bonding layer 304.

Figure 46 (a1) shows temperature distribution data at 0°C/cm. Figure 46 (a2) shows temperature distribution data at 500°C/cm. Figure 46 (a3) shows temperature distribution data at 1000°C/cm. Figure 46 (a4) shows temperature distribution data at 1500°C/cm. Figure 46 (a5) shows temperature distribution data at 2000°C/cm.

Figure 46(b) is a graph showing the relationship between the temperature from the hot side copper plate 104a to the cold side copper plate 104b and each temperature gradient in Figure 46(a). The square frames in Figure 46(b) indicate the locations where the temperature gradients were measured.

46(b), in the method for evaluating a bonding layer of the present invention, the temperatures of the hot-side copper plate 104a and the cold-side copper plate 104b can be set arbitrarily by independently controlling the heat generation of the heater chip 109a and the heater chip 109b. Also, the temperature gradient can be set arbitrarily.
Therefore, EM testing can be performed without melting even at high current densities, and appropriate TM testing can also be performed.

Although the present specification has described the present invention in detail based on the embodiments, the present invention is not limited thereto, and various modifications are possible without departing from the spirit and scope of the present invention.
It goes without saying that the matters or contents described in this specification and the drawings can be combined with each other.

It is now possible to easily detect deterioration of the bonding layer between electrodes, etc., non-destructively, based on measurement data of temperature distribution. It also makes it easy to evaluate the lifespan of solder bonding layers, etc. It can also be used to detect deterioration and evaluate the reliability of lifespan evaluation.

101 heating/cooling plate 102 circulating water pipe 103 chiller 104 copper plate 105 solder layer (joint layer, joint)
106 SiC substrate 107 Polyimide sheet (polyamide)
108 Infrared thermography camera 109 Heater chip 110 XYZ stage 111 Ni-P film (plating film)
112 Gold plating film 114 Temperature probe terminal electrode (gold plating film)
115 Thin film heater terminal electrode (gold plating film)
116 Temperature probe (Ni-P film)
117 Thin film heater (Ni-P film)
118 heat dissipation (heat transfer) grease 119 roughened surface 120 masking tape 121 lead wire 122 voltmeter 123 solder 124 electromigration (EM) terminal electrode (gold plating film)
125 Sintered Ag paste filling layer 126 High temperature solder 127 Wiring 128 Current 129 Copper plate (heat sink)
130 Cross mark 131 Through hole (TH)
132 Current application path 134 Sintered Ag paste filling portion 301 Tin (Sn) layer 302 Solder resist (SR) layer 304 Bonding layer (bonding portion)
305 Volt 501 Mask (including alkali-soluble acrylic polymer)
502 Laser light (femtosecond laser light)
503 Recess 504 Sn-Pd catalyst 801 Switch circuit 802 Constant current circuit 803 Current power supply device 804 Control circuit 901 Diffusion section

Claims (9)

A base substrate having insulating or semiconducting properties;
a heater disposed on a first surface of the base substrate;
a current application path disposed adjacent to the heater on a first surface of the base substrate;
A first plate;
a first substrate or sheet;
a bonding layer formed between the first plate and the first substrate or sheet;
A resin membrane or a resin film arranged in contact with the bonding layer;
a temperature measuring device for measuring a temperature of the bonding layer through the resin membrane or resin film;
a filling layer that bonds the first plate and the base substrate;
a first power supply device that applies a first current between the heater and the current application path ;
The migration evaluation device is characterized in that the heat generated by the heater heats the bonding layer . A base substrate having insulating or semiconducting properties;
a heater disposed on a first surface of the base substrate;
a current application path disposed adjacent to the heater on a first surface of the base substrate;
a first power supply device that applies a first current between the heater and the current application path;
a second power supply device that applies a second current to the heater;
A first plate;
a first substrate or sheet;
a bonding layer formed between the first plate and the first substrate or sheet;
A resin membrane or a resin film arranged in contact with the bonding layer;
a temperature measuring device for measuring a temperature of the bonding layer through the resin membrane or resin film;
a filling layer that bonds the first plate and the base substrate;
The heat generated by the heater heats the bonding layer,
The migration evaluation device, wherein the first current is applied to the current application path through the filling layer. A base substrate having insulating or semiconducting properties;
a heater disposed on a first surface of the base substrate;
a current application path disposed adjacent to the heater on a first surface of the base substrate;
A first plate;
a first substrate or sheet;
a bonding layer formed between the first plate and the first substrate or sheet;
A resin membrane or a resin film arranged in contact with the bonding layer;
a temperature measuring device for measuring a temperature of the bonding layer through the resin membrane or resin film ;
a filling layer that bonds the first plate and the base substrate ;
The migration evaluation device is characterized in that the heat generated by the heater heats the bonding layer . A base substrate having insulating or semiconducting properties;
a heater disposed on a first surface of the base substrate;
a current application path disposed adjacent to the heater on a first surface of the base substrate;
a temperature probe disposed on a first surface of the base substrate, the resistance value of the temperature probe varying depending on the temperature of the heater;
A first plate;
a first substrate or sheet;
a bonding layer formed between the first plate and the first substrate or sheet;
A resin membrane or a resin film arranged in contact with the bonding layer;
a temperature measuring device for measuring a temperature of the bonding layer through the resin membrane or resin film;
a filling layer that bonds the first plate and the base substrate ;
The heat generated by the heater heats the bonding layer,
The base substrate has a through hole formed therein,
the filling layer bonds the first plate and the base substrate and fills the through hole;
The migration evaluation device is characterized in that the filling layer is connected to the heater. A base substrate having insulating or semiconducting properties;
a heater disposed on a first surface of the base substrate;
a current application path disposed adjacent to the heater on a first surface of the base substrate;
a first power supply device that applies a first current between the heater and the current application path;
a second power supply device that applies a second current to the heater;
A first plate;
a first substrate or sheet;
a filling layer that bonds the first plate and the base substrate;
a bonding layer formed between the first plate and the first substrate or sheet;
A resin membrane or a resin film arranged in contact with the bonding layer;
A temperature measuring device is provided for measuring a temperature of the bonding layer through the resin membrane or resin film ,
The migration evaluation device is characterized in that the heat generated by the heater heats the bonding layer . the base substrate is silicon carbide (SiC);
6. The migration evaluation device according to claim 1, wherein the heater is made of at least one of Ni and Ni--P. the heater is a thin film heater,
The film thickness of the thin film heater is 0.1 (μm) or more and 7.5 (μm) or less,
6. The migration evaluation device according to claim 1, wherein the sheet resistance (Ω/sq) of the film thickness of the thin film heater is 0.25 (Ω/sq) or more and 1.00 (Ω/sq). the base substrate is silicon carbide (SiC);
6. The migration evaluation device according to claim 1, wherein the bonding layer is made of solder. Further comprising a moving stage,
The temperature measuring device is mounted on the moving stage,
6. The migration evaluation apparatus according to claim 1, 2, 3, 4 or 5, wherein the moving stage is moved to measure the temperature, the temperature difference or the temperature distribution of the bonding layer.

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